Boston Marathon Bombers in Shoot Out With Police on MIT Campus

One alleged bomber is believed to be dead or in custody, the second is on the run, following an intense gun battle on MIT campus that left a university police officer dead.

A major police operation is underway in Watertown, near Boston, over the latest shooting incident which killed a police official on MIT campus.

The suspect still at large (seen above wearing the white hat) is on the run armed with a combat rifle.

Police personnel continue to descend on the scene which quickly turned chaotic following the gunfire.

Two young men believed to be fully armed with explosives and gun were involved in the standoff according to reports, after hijacking a Mercedes car. The driver later escaped.

Local reports suggest explosives were also been detonated in the operation. Injuries have been reported as witness say victims have been taken to hospital.

Police officials suspect the latest incident could have a strong connection with the Boston Marathon bombing which took place earlier.

"They [gunmen] lit it, still in the middle of the gunfire, and threw it. But it went 20 yards at most," an onlooker told the New York Times.

A police official speaking to reporters on the scene that one of the suspects has been detained while another one continues to be "on the loose." Other reports said a suspect had been killed in the gun battle.

Over 200 heavily armed officers, including armoured cars, have descended on the leafy campus

The FBI, which is leading the hunt for the Boston Marathon bombers, is reported by US media to be on the scene at Watertown.

The campus of the prestigious MIT was on lockdown following the shooting, and police could be seen swarming around the university's Stata Center.

The university later issued a statement to say the campus is now safe but urged students to "remain vigilant".

Earlier, the FBI released photos of two suspects it said it wanted to identify as part of its investigation into the bombings at the Boston Marathon that killed three people and wounded more than 170.

The FBI, which is leading the hunt for the Boston Marathon bombers, is reported by US media to be on the scene at Watertown.

The campus of the prestigious MIT was on lockdown following the shooting, and police could be seen swarming around the university's Stata Center.

The university later issued a statement to say the campus is now safe but urged students to "remain vigilant".

Earlier, the FBI released photos of two suspects it said it wanted to identify as part of its investigation into the bombings at the Boston Marathon that killed three people and wounded more than 170.