One suspect is dead while another is still at large after a gun fight with police in Watertown, near the site of the Boston Marathon bombings.
10.56pm: More details emerge on the identity and background on Dzhokhar Tsarnaev. He received a City Scholarship from the City of Cambridge, Massachusetts, in May 2011, a Cambridge local government announcement reveals.
10.47pm: Live images from Watertown show police surrounding a house. CNN says live video broadcasts from the scene are being put on a delay in an effort to avoid broadcasting anything "unduly violent".
10.30pm: Boston Police release an image of the remaining suspect, confirmed to be 19 year-old Dzhokhar Tsarnaev.
10.18pm: Governor Patrick asks Boston residents to remain inside as search for suspect continues.
10.15pm: Information is beginning to emerge about the remaining suspect in the Boston marathon bombings, Dzhokhar Tsarnaev. He and his brother are said to be from an area of Russia close to Chechnya - but have lived in the US for at least a year.
10.03pm: Police colonel Timothy Alan says their number one priority is to make the neighbourhoods of Watertown safe. He says the situation in Boston "may take hours" to resolve, but they are making progress.
8.49pm: Police have come across another suspicious bag.
8.45pm: More details are coming to light about the suspects movements earlier this evening. Two men allegedly hijacked a car, forcing an unknown man to drive them, before letting him go unharmed.
8.40pm: Police have stopped a taxi at Kenmore Square and taken two men out of the car at gunpoint. News footage shows two men handcuffed and sitting on the curb.
8.32pm: Dozens of heavily armed police are entering an area of Watertown.
The AP have reported the suspect as a 19-year-old Chechan man from Cambridge, however this is not confirmed.
7.40pm: There is some speculation that this photo -- taken during the aftermath of the Boston Marathon bombings and posted on Facebook -- shows one of the two suspects (Far right, behind the three people crossing the road).
7.37pm: Shop workers and owners have been told not to go to work today if their work is in the vicinity of 480 Arsenal, which appears to be a small shopping centre.
7.22pm: Doctors have confirmed the suspect was brought in under police guard in with "traumatic arrest" and was pronounced dead at 1.35am local time. They gave no information on his identity, only saying "it's an adult male."
They said he was suffering from "multiple wounds" including "blast injuries".
6.44pm: A bomb squad robot is checking suspicious cars in the area.
6.40pm: There are several unconfirmed reports of explosive devices in the area, and that one or both of the suspects had explosives strapped to their chest.
6.20pm: A press conference with Boston police has confirmed one suspect was shot by police and later died in hospital.
The two suspects were in a car and police tried to apprehend the men, said a spokesman.
"Several explosive devices were discharged from the car at police officers."
"One was struck and taken into custody. The other was able to flee from the car and there is an active search on at this time."
He did confirm the man in the white cap is the suspect still on the run.
"We believe this to be a terrorist. We believes this is a man who has come here to kill people."
The Cambridge Police statement can be read in full here.
6.17pm: Police have released a CCTV image of the suspect (still at large) taken last night at a 7/11.
CNN reports the suspect was injured in a car chase and taken to hospital where he later died.
6.08pm: The Boston Police Commissioner Edward Davis has confirmed that the suspect arrested earlier has died, and one is still at large 'armed and dangerous". The man still on the run is the suspect depicted wearing a white hat in FBI-released photographs.
5.46pm: A transit police officer has also been shot and wounded during tonight's events.
Jennifer Peter is the Metro editor at the Boston Globe:
"MBTA spokesman: A transit officer is being treated at a local hospital for gunshot wounds...To be clear, the shooting of the transit officer is related to the rest of the mayhem this evening."
5.31pm: Susan Candiotti, a senior correspondent for CNN says she can not get confirmation from law enforcement officials that the gunmen are suspected of the Boston bombing.
5.09pm: The following video was filmed at Watertown, according to US media.
5.00pm: Unconfirmed reports say the second suspect is a Brown university student reported missing several months ago. Dispatch has reportedly named the two men.
4.56pm: Reports suggest the suspect still at large is the man wearing a white hat in photos released by the FBI of the marathon bomber suspects.
(Verification source: Below is a tweet from reporter on the scene. it was replied to by another man who said he heard the same).
4.39pm: Police have confirmed they are still searching for a second suspect. A statement from Massachusetts State Police, read aloud on CNN, said that "multiple explosive devices" were used against police tonight.
4.34pm: Boston media reports one Boston marathon bombing suspect is in custody and another is still on the loose after a gun battle -- still ongoing --with police in nearby Watertown.
The Boston Globe cites "an official with knowledge of the investigation" that the events in Waterstone are related to the bombing, and calls the gunman already arrested a "bombing suspect".
One of the world's most prestigious universities was forced into lockdown when a campus police officer was shot dead in an incident that may be linked to the Boston marathon bombings.
The Boston Globe reports police captured one of the Boston marathon bombing suspects early Friday but are still chasing a second suspect in a manhunt in which gunfire and explosions were heard.
The suspect was caught in Watertown near the US city of Boston after a chase which started with the killing of a police officer at the elite Massachusetts Institute of Technology, the newspaper reports.
The officer had been responding to a report of a disturbance on the Massachusetts Institute of Technology (MIT) campus at 10.30pm Thursday night local time when he was shot multiple times.
He was taken to a hospital where he was pronounced dead from his wounds.
A statement from the Middlesex district attorney's office and Cambridge police said there were no other victims in the MIT incident.
The shooting came little more than three days after the twin bombings on the Boston
Marathon that killed three people, wounded more than 180 others and led to an increase in security across the city.
Shortly after, police descended en masse in nearby Watertown, just north of MIT, following reports of a carjacking.
Shortly after, gunfire and explosions erupted in streets in Watertown, north of the university.
"There were blasts, it could have been grenades," local resident Adam Brown told AFP.
The NBC-WJAR channel showed film of a man lying on the ground in a street in the town and surrounded by police.
Authorities have made no immediate link between the incidents.
MIT immediately posted a warning to students on its website about the incident.
"MIT worked with multiple police departments in order to ensure the safety of the MIT campus.
Police officers swept the campus in search of the shooter, and MIT sent text and email messages to the members of the MIT community asking them to stay indoors while the search continued."
The shooting took place about 10:30pm local time outside an MIT building, according to state police spokesman Dave Procopio.
At around 2am, MIT Police determined that the suspect was no longer on campus, and that it is safe to resume normal activities.
"However, the MIT Police ask that members of the MIT Community remain vigilant in the coming hours," it said in a statement.
About 11,000 people attend the university.
The university said it was "heartbroken by the news that an MIT Police officer was shot and killed in the line of duty"
"Our thoughts are now with the family."