Two brothers suspected of bombing the Boston Marathon killed an MIT police officer Thursday night, as they threw explosives during a car chase and gun battle that killed one man in question and left the other on the loose.

The suspects, Dzhokhar and Tamerlan Tsarnaev, are from a southeastern part of Russia near Chechnya, according to the Associated Press.

Tamerlan, an FBI Suspect No. 1, was killed in the high-speed chase that ripped through Watertown, Massachusetts.

The younger Tsarnaev escaped the standoff, and is now on the run.

Suspect No. 1 was seen in surveillance footage at the marathon wearing a black baseball hat, while his 19-year-old brother, suspect No. 2, was caught on tape wearing a backwards cap in white.

Suspect No. 1 met his demise hours following the FBI's release of photos and video footage, asking for help from the public in finding them. 

The images depict the brothers walking single file near the finish line. Suspect No. 2, wearing the white hat, set down a bag at the site of the explosions.

Late Thursday night, Suspect No. 2 was seen on surveillance tape robbing a convenience store in Cambridge, near MIT. He shot and killed a university police officer as well, who came to the scene in response to a call reporting the disturbance.

The two brothers then stole a Mercedes-Benz from a driver, forcing him out of the vehicle and speeding away from a gas station in Cambridge.

Police received calls of the stolen vehicle, which led to a chase that ended in Watertown, where the suspects threw explosives from the car, in addition to opening fire. Authorities say that a police officer was injured during the chase.

Christine Yajko, a Watertown resident, told AP she woke to the noise of an enormous explosion at about 1:30 a.m.

"I heard the explosion, so I stepped back from that area, then I went back out and heard a second one," she recounts. "It was very loud. It shook the house a little."

Suspect No. 1 died from blast injuries and multiple gunshot wounds.

The entire city of Boston is now on lockdown, as a mass manhunt for the two men has led to the suspension of public and mass transit; citizens have been advised to stay indoors, businesses remain closed and people standing on subway platforms and bus stops were told to return home.