The suspect, identified as Dzhozha Tsarnaev, 19, was found hiding in a boat in the backyard of a Watertown neighbourhood.
According to Reuters, the suspect was captured alive with serious injuries, and was taken to the Massachusetts General Hospital.
UPDATE (7.33pm): Authorities are still hunting for the second suspect. They have been identified as Chechen brothers. Chechnya is a Muslim area in Russia that has been fighting a separatist war against Russian authorities which ended in 2009.
They were both permanent citizens of the United States. One brother is still on the run and is thought to be carrying explosives. The city of Boston has been shut down, schools closed and people told not to go to work.
UPDATE (5:47pm): At a press conference, doctors reported that the first suspect died from multiple gunshots and possibly wounds from explosion.
The state of Massachusetts has been rocked by violence once again. What began as a fatal shooting of a campus officer in the Massachusetts Institute of Technology has led to the death of one suspect of the Boston Marathon bombings and a manhunt for the other.
At approximately 10:20pm Thursday night (US Eastern time), police received reports of shots fired on the MIT campus. At 10:30pm, an MIT campus police officer was found dead in his vehicle in the area of Vassar and Main streets.
After shooting the police, the two men who were believed to be suspects for the Boston Marathon Bombing hijacked a car.
Police received reports of the carjacking in the area of Third Street in Cambridge. Police found the vehicle and chased it into Watertown a suburb neighbouring MIT.
Shooting broke out between police and the two suspects. Resident Andrew Kitzenberg, 29, said he looked out of this third-floor window to see two young men of slight build in jackets shooting at dozens of police officers from behind a black Mercedes SUV. The officers and the men were 70 metres apart, he said, and engaged in “constant gunfire.”
The two shooters threw explosives and were seen to have possessed a bomb which shaped like pressure cooker. After the bomb exploded, one of the men ran toward the gathered police officers and was tackled. The other jumped back into the SUV and escaped. The man in custody was taken to hospital where he died.
An extensive manhunt is ongoing in the Watertown area for the second suspect, who is believed to be armed and dangerous. Police had told residents to not open their doors as they conduct a door-to-door, street-by-street search. Buses are being sent in to evacuate residents.