WATERTOWN, Mass. —
"We believe this man to be a terrorist," Boston Police Commissioner Ed Davis said. "We believe this to be a man who's come here to kill people."
Some neighborhoods resembled a military encampment, with officers patrolling with guns drawn and aimed, residents peering nervously from windows and people near surrounded buildings spirited away.
The bloody turn in the case came just hours after the FBI released photos and video of two suspects in the bombing and asked for the public's help in identifying and catching them.
Authorities said the man dubbed Suspect No. 1 — the one in sunglasses and a dark baseball cap in the surveillance-camera pictures — was Tamerlan Tsarnaev, while Suspect No. 2, the one in a white baseball cap worn backwards, was his brother.
The bombings on Monday near the Boston Marathon finish line killed three people and wounded more than 180, tearing off limbs in a spray of shrapnel and sparking fears across the nation that another terrorist attack had come to U.S. soil.
Chechnya has been the scene of two wars between Russian forces and separatists since 1994, in which tens of thousands were killed in heavy Russian bombing. That spawned an Islamic insurgency that has carried out deadly bombings in Russia and the region, although not in the West.
But investigators have shed no light on the motive for the Boston Marathon bombing and said it was unclear whether any terrorist organizations had a hand in it.
The FBI was swamped with tips after the release of the photos — 3,000 every second by one estimate — but what role those played in the overnight clash was unclear. State Police spokesman Dave Procopio said police realized they were dealing with the bombing suspects based on what the two men told a carjacking victim during their getaway attempt.