Boston Marathon bombing: One suspect Tamerlan Tsarnaev dead, 19-year-old Dzhokhar Tsarnaev on the run
Explosions were heard at a Boston home this morning as police continue to hunt for a marathon bombing suspect and another possible accomplice.
One of the terrorists is dead and the second is on the loose and said to be 'armed and dangerous' after a dramatic shootout in the suburbs of the city on Thursday night.
SWAT teams surrounded a house in Watertown on Friday morning following a massive rush of police vehicles through the area.
'Suspect 2', 19-year-old Dzhokhar Tsarnaev, seen on CCTV wearing a white baseball cap, is on the run and reportedly has explosives strapped to his body.
The terrorist, dubbed 'Suspect 1' by the FBI, has been named as Tamerlan Tsarnaev, 26. He died in hospital from gunshot wounds and possible blast injuries after a fierce gun battle rocked the Watertown area hours after a police officer was shot dead at the nearby MIT campus.
Tamerlan reportedly had a bomb strapped to his chest when he was killed while he and his brother robbed a 7-Eleven, tried to steal an SUV and threw explosives at police officers.
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Fast-paced: SWAT teams enter a suburban neighborhood around 9am on Friday to search for the remaining suspect in the Boston Marathon bombings in Watertown, Massachusetts
Escape: A neighbor is escorted to safety as police surround a home while searching for a suspect in the Boston Marathon bombings
Tightening the noose: SWAT teams close in on a property in the Watertown area
Dramatic moment: Police vehicles screamed through the town of Waterdown, Mass. on Friday morning as police continue to hunt for one of the terrorists
Terrorists: Tamerlan Tsarnaev (left) was killed during an exchange of gunfire with police on Wednesday night. His younger brother Dzhokhar (right) is still on the run and reportedly has explosives strapped to his body
Dzhokhar Tsarnaev posted online he will 'kill everyone because we killed his brother', according to a dispatcher in Watertown.
Two people have been taken into custody at the home in Cambridge where the brothers grew up but are not considered suspects. The home is surrounded by FBI and a bomb squad van is on the scene.
The entire city of Boston is on lock down with residents warned to stay indoors, public transport shut down and a no-fly zone around the city.
A transit police officer was critically wounded in the exchange of gunfire with the suspects.
Dzhokhar and Tamerlan Tsarnaev are believed to be legal immigrants to the U.S., from the Russian region of Chechnya which has been plagued by an Islamic insurgency stemming from separatist wars.
Lock-down: Police patrol a neighborhood in Watertown as officers go door to door during the manhunt on Friday morning
Last seen: 'Suspect 2' Dzhokhar Tsarnaev pictured in 7-11 last night shortly before a shoot-out with police which left one officer dead and the second suspect
Dzhokhar was born in Kyrgyzstan, according to NBC. His brother Tamerlan was reportedly born in Russia. The brothers are believed to have moved to America with their family in 2002 or 2003.
The 19-year-old, who attended Cambridge Rindge and Latin School, is an amateur wrestling champion who holds a Massachusetts driving license. The older brother Tamerlan attended Bunkerhill Community College and was studying to become an engineer but took a year off to pursue boxing. He is a two-time Golden Glove champion.
A friend of the brothers told CNN that he had known them since 2006 and they were 'normal kids' who partied and occasionally smoked.
A classmate told CBS that Dzhokhar did not have an accent and that he believed he had always lived in the U.S.
The father of the suspects said that his son Dzhokhar is a smart and accomplished young man. Anzor Tsarnaev spoke by telephone from the Russian city of Makhachkala on Friday.
Anzor Tsarnaev said: 'My son is a true angel. Dzhokhar is a second-year medical student in the U.S. He is such an intelligent boy. We expected him to come on holidays here.'
Flushing him out: SWAT teams along with Boston police flooded into suburban areas of the city during a fast and fluid investigation
On his tail: SWAT teams train their weapons toward as house from the roof of a shed as they carry out door-to-door searches for the fugitive terrorist
Dangerous operation: A bomb squad officer uses a robot to remove an item, believed to be a water bottle, from the back of the car allegedly used by the suspects
On the run: This image provided by the Boston Regional Intelligence Center shows Dzhokhar A Tsarnaev, one of the suspects in the Boston Marathon bombings
Swarming the streets: Dozens of armed officers check houses in the suburb of Watertown after the second suspect fled during a car chase and firefight
Plan of action: Police convene on School and Walnut Street in Watertown, Massachusetts, after a fierce gun battle with the terrorists, one of whom died from multiple bullet wounds
Is this their man? This photograph was tweeted by a resident near the shoot-out who claims it is one of the suspects fleeing on foot next to a scorch mark on the pavement
The drama unfolded hours after the FBI released images of two men named as suspects in the Boston blast which killed three and injured 176 on Monday.
The Middlesex district attorney said the two men are suspected of killing a Massachusetts Institute of Technology police officer on campus in Cambridge late last night, then stealing a car at gunpoint.
Dozens of police officers, FBI agents, national guard, K-9 units and SWAT teams rushed to Watertown after midnight after a reported car chase involving the two suspects in a black 2013 Mercedes.
A short time later, police received reports of a carjacking by two men who kept their victim inside the car for about half an hour, the statement said.
Police pursued that car to Watertown, where explosives were thrown from the car at police and gunfire was exchanged, the statement said.
'During the exchange of the gunfire, we believe that one of the suspects was struck and ultimately taken into custody.'
A doctor from Beth Israel Deaconess Medical Center said the suspect died after suffering multiple wounds from gunshots and possibly the blast of an explosive.
'There were signs of more than just gunshot wounds, said the doctor, who did not give his name.
'A second suspect was able to flee from that car and there is an active search going on at this point in time,' Colonel Timothy Alben, superintendent of the Massachusetts State Police, told a news conference.
'What we are looking for right now is a suspect consistent with suspect No 2, the white-capped individual who was involved in Monday's bombing of the Boston Marathon,' Alben said.
Police say the two suspects discharged several explosives at police from the vehicle during the pursuit.
According to eyewitness reports, two men believed to be in their early twenties engaged in a furious gun fight with dozens of police on a backstreet of Watertown.
Suspects: Dzhokhar Tsarnaev, 19, (pictured left) is the subject of a massive manhunt by police while his older brother Tamerlan (right) was shot dead by police during an exchange of gunfire
Armed and ready: Police officers aim their weapons as they close in on two suspects in the Boston bombings after a university officer at MIT was shot dead on campus
Gun battle: Police officers draw weapons from behind a car during a dramatic shoot-out with two of the suspects in the Boston Marathon bombings
Warning: Boston Police Commissioner Ed Davis tells the media that there is a terrorist on the loose who wants to kill people and tells people not to open their doors
Connections: A map showing the locations of the Boston Marathon bombings, the MIT campus where a police officer was shot dead and the suburb of Watertown where the gunfight broke out
TIMELINE OF TERROR: HOW EVENTS UNFOLDED IN BOSTON
Andrew Kitzenburg spoke to the New York Times about the view he had from his third floor window as he saw two men in jackets shooting at at least 10 police from behind a black Mercedes SUV.
The gun battle was being waged 70 yards apart and Mr. Kitzenburg said that the two men and police were engaged in 'constant gunfire'.
Suddenly a police SUV 'drove towards the shooters' and was fired upon until it was damaged and rolled to the side of the road, crashing into two cars in his driveway.
Dramatically, Mr. Kitzenburg said the two gunmen then threw a large bomb, 'They lit it, still in the middle of the gunfire, and threw it. But it went 20 yards at most.
The unknown device did explode and at that point, one of the men ran towards the gathered police officers and was tackled - it is not clear from Mr. Kitzenburg if he was shot or not.
Then suddenly, the other man returned to his SUV and drove towards police officers and 'put pedal to the metal'.
The car 'went right through the cops, broke right through and continued west.'
Mr Kitzenburg said that the two men had left backpacks by the car and that a police bomb robot was currently dealing with the devices.
Police have told all residents to remain in their homes while they clear the area.
Police screamed at reporters on the scene to turn off phones 'if they want to live' as they hunted for the suspects - fearful that improvised explosives could be remotely detonated.
The shoot-out came hours after the FBI released images and video of the Boston bombing suspects as they launched a hunt for two 'armed and extremely dangerous' men.
The images show them walking in single file toward the finishing line of the race around 13 minutes before the twin detonations.
Hours after the initial photos were made public, investigators released close-up shots this morning of the two suspects that more clearly show the men's faces.
Suspect Number One was wearing a black baseball hat, a dark hooded jacket and khaki pants.
Suspect Number Two was wearing a white basketball cap on backwards and a dark hooded sweatshirt.
The FBI made no mention of the men's height, weight or age range and would not discuss the men's ethnicity.
'It would be inappropriate to comment on the ethnicity of the men because it could lead people down the wrong path potentially,' said FBI agent Greg Comcowich, a spokesman for the Boston FBI office.
The information on the first suspect was developed within a day or so before its release, DesLauriers said.
Agent Daniel Curtin said the FBI did not issue the photos earlier because authorities wanted to be meticulous: 'It's important to get it right.'
And according to FBI sources who have spoken to CNN, still unreleased footage reveals that the suspects stayed at the scene to watch the devastation the two blasts created.
'When the bombs blow up, when most people are running away and victims were lying on the ground, the two suspects walk away pretty casually,' said the official to CNN, who has seen the unreleased video.
'They acted differently than everyone else,' he added.
VIDEO Lay down. Show me your hands. Mobile footage claims to show gun battle
Vigilant: Police officers stand in a shopping mall as the search for the 'Suspect 1' continues
Hunt: Police officers with their weapons out search for a suspect on the streets of Watertown
Alert: A police officers rides in the back of a van with his weapons out following a tense night of police activity
Link: It's not clear whether the incident which unfolded tonight is related to the Boston bombing on Monday
False alarm: A man lies spread out on the ground as police trains their weapons on him, however it is thought he is not of the suspects
Shoot out: According to eyewitness reports, two men believed to be in their early twenties engaged in a furious gun fight with dozens of police on a backstreet of Watertown
Massachusetts State Police spokesperson Dave Procopio said that they believe multiple possible explosive devices were used against police tonight during this incident at Watertown
Witnesses reported hearing explosions and gunfire as the police apparently engaged the two men and local television footage showed one man lying spread out on the ground, with his arms out, surrounded by police.
However, it is now thought that this man is not one of the suspects wanted by law enforcement.
Police officials would not discuss the incident with reporters.
When asked for information on the incident, Boston police spokeswoman Neva Coakley frantically told MailOnline, 'I don't know anything... I don't know anything at this point.'
An officer at the Waterdown police department responded similarly to questions about the incident, saying only, 'They are out in the street, that's all I know,' before hanging up the phone.
Stand-off: A police officer trains his weapon as chaos descends on Boston after multiple shots and explosions were heard in the suburb of Watertown
On alert: Police search neighborhoods yard by yard after a chase and shoot-out with two heavily armed men following the shooting of an MIT police officer
As the battle raged, police urged everyone to stay inside of their homes. The area is still considered extremely dangerous.
Massachusetts state police spokesman Frank Schifone told MailOnline that only one suspect is accounted for and he’s in the hospital.
Asked whether there is any tie between tonight’s incidents and the marathon bombings, he said, ‘At this time we don’t know. It’s all unfolding.’
Initial reports suggest that one suspect is in custody and a police officer has been injured.
Earlier, Cambridge police and the Middlesex District Attorney's office confirmed an officer was shot dead responding to a report of a disturbance when he was fired upon multiple times.
He later died at a hospital. His name was not immediately released.
State police spokesman Dave Procopio says the shooting took place about 10:30 p.m. outside an MIT building.
Procopio says authorities are searching for a suspect or suspects. No arrests have been made.
MIT police, Cambridge police and state police are involved in the investigation.
About 11,000 people attend the prestigious school.
The campus website said police were sweeping the campus and urged people to stay indoors.
In a statement issued to the press, law enforcement officials said that no arrests have been made in the shooting and the search for a suspect or suspects is ongoing.
Chaos: In a photograph captured by David Green, a man closely resembling suspect Number Two in the Boston Marathon bombings (pictured far left in a white baseball cap) is seen calmly walking away from the scene