The Boston Marathon bombing investigation took a dramatic turn overnight as two suspects sought by federal authorities fought local police in a violent exchange of bullets and explosions.
By early Friday one of the suspects and a Massachusetts Institute of Technology campus police officer were dead, another police officer was wounded, and the remaining suspect had fled into nearby Watertown, Mass. The area is under lockdown as police conduct a house-to-house search for a man presumed to carry firearms and bombs.
Authorities shut down Boston public transit and warned residents of a huge swath of close-in suburbs to hunker down. Officials said the suspect at large is the second of two identified on Thursday in video and photo stills released to the public – known since as suspect No. 1 and suspect No. 2. In those images, he was wearing a white hat turned backwards and a gray hooded sweatshirt.
According to the Associated Press, the suspects are brothers from an area of Russia near Chechnya. The AP said sources have identified the suspect who remains at large as Dzhokhar A. Tsarnaev, 19, of Cambridge, Mass.
“We believe this to be a terrorist,” Boston Police Commissioner Ed Davis said. “We believe this to be a man who came here to kill people.”
The exact sequence of events remained unclear Friday morning as news accounts of the suspects’ actions differed.
About 10:30 p.m. Thursday, police received a report of a robbery at a convenience store in Kendall Square, a Cambridge neighborhood near the MIT campus. Shortly afterward, authorities discovered an MIT police officer shot dead at Main and Vassar Streets, according to The Boston Globe.
Authorities on Friday morning had not yet determined the exact relationship of these events. According to a statement from the Middlesex District Attorney’s Office and Cambridge police, the MIT officer had been responding to reports of a “disturbance.”
NBC News reported that the two suspects car-jacked the MIT officer’s cruiser. Other accounts said the police officer was discovered in his car.
Shortly afterward, the two suspects car-jacked a Mercedes sport utility vehicle at gunpoint, briefly imprisoning the driver in the car.
The driver was subsequently able to escape at a gas station along Memorial Drive, a major area thoroughfare that connects Cambridge with suburbs to the west. The two suspects drove off along Memorial Drive toward Watertown, with a train of law enforcement vehicles in pursuit, according to the Globe.
Authorities exchanged gunfire with the suspects during the chase. In the exchange, a transit officer was wounded, according to police.
The suspects apparently were then cornered in an area of Watertown and exited their hijacked SUV to continue the firefight. Citing eyewitnesses, The New York Times depicted a wild scene in which two slightly built young men traded volleys of gunfire with approaching police.
One of the men had a device that resembled a pressure cooker, one witness told the Times. Pressure cookers were used in the bombs left Monday along the Marathon route, according to the FBI.
In the Watertown battle, the suspect “lit” the pressure cooker and tossed it toward police, said the Times. But it went only 20 yards or so and did not endanger officers when it exploded, according to this account.
Eventually one of the two men ran toward police officers. He was tackled or shot. The remaining suspect got back into the SUV, turned it toward a police cordon, and blasted through at full throttle.
Doctors at Beth Israel Deaconess Medical Center in Boston said they had treated a man with multiple gunshot wounds and explosive trauma early Friday morning. The man died. Hospital officials were unable to confirm whether the deceased was the FBI's suspect No. 1.
However, law enforcement officials announced at an early-morning press conference that a suspect was dead. They said the two men who had fought with police were the same two men depicted in the photos released to the public on Thursday.
The man still at large on Friday morning, they said, is suspect No. 2. Surveillance video depicts him placing a bag in the area of the second Boston Marathon bomb.
“There is a terrorist on the loose,” said one police officer at the impromptu press conference.
Police warned residents from Cambridge out to Newton to stay indoors and not to answer their doors except for an identified police officer. They told businesses to keep closed. Boston schools were closed, as well as all Boston-area public transit, including subways, trains, and buses.
“People at bus or subway stations, we are asking them to go home,” said Kurt Schwartz, head of the Massachusetts state Homeland Security Department, at a 6 a.m. press conference. “We do not want people congregating and waiting for the system to come back on.”