A late-night police chase and shootout has ended with one marathon bombing suspect dead and another on the run, Boston Police commissioner Ed Davis said early Friday morning. One police officer was killed and another seriously wounded during the pursuit.

The latest reports are coming form various news organizations including Yahoo News, which says Federal agents swarmed neighboring Watertown after local police were involved in a car chase and shootout with at least one of the suspects. During the pursuit, officers could be heard on police radio traffic describing the suspects as having grenades and other explosives.

According  to Yahoo News,  last night about 10:30, a robbery was reported at a 7-Eleven in Cambridge, Davis said. An MIT officer responding to the robbery was shot, and later pronounced dead. The suspects fled in a stolen Mercedes-Benz. Watertown Police spotted car and shots were fired between police and the suspects.

One suspect was shot by police and later died, but the second fled on foot, and a tense manhunt ensued.

"We believe this to be a terrorist," Davis told reporters at a hastily arranged press conference in Watertown. "We believe this to be a man who has come here to kill people. We need to get him into custody."

An MTA officer was seriously wounded during the exchange of gunfire, Davis said.

The FBI has yet to publicly confirm a connection between the events in Watertown and the twin explosions that killed 3 people and injured 170 others at the Boston Marathon on Monday. But according to Boston Police, the suspect who remained at large—a.k.a Suspect Two—was the "one in the white hat" seen in the photos released by the bureau on Thursday.

In a radio alert  issued to fellow officers, the suspect was described as a "white male with dark complexion or a Middle Eastern male with thick curly hair wearing a charcoal gray hooded sweatshirt ... possibly with an assault rifle and explosives." Police in Watertown, Newton, Brighton and Cambridge were put on high alert as the suspect was said to be armed with a "long gun."

 

"Suspect 2" (FBI.gov)

Dozens of police officers, many of them off-duty, searched backyards in search of the second suspect, and a police perimeter of several blocks was established. K9 units and SWAT teams searched homes on Spruce Street as officers searched an SUV that the suspects had abandoned. Multiple devices were left in the road and two handguns were recovered, according to police scanners.

The Watertown shootout occurred after a gunfight erupted near the Massachusetts Institute of Technology, where the MIT police officer was shot and later died. The campus was placed on lockdown for several hours, and students were told to remain indoors.

At approximately 3:30 a.m., Massachusetts State Police issued a plea on Twitter for residents of Watertown to lock their doors and not open them for anyone as they searched backyards and exteriors of houses there.

"Residents in and around Watertown should stay in their residences," the alert read. "Do NOT answer door unless it is an identified police officer."