WATERTOWN, Mass. —
Exactly how the long night of crime began was marked by conflicting reports. But police said the brothers carjacked a man in a Mercedes-Benz in Cambridge, just across the Charles River from Boston, then released him unharmed at a gas station.
They also shot to death a Massachusetts Institute of Technology police officer, 26-year-old Sean Collier, while he was responding to a report of a disturbance, investigators said.
The search for the Mercedes led to a chase that ended in Watertown, where authorities said the suspects threw explosive devices from the car and exchanged gunfire with police. A transit police officer, 33-year-old Richard Donohue, was shot and critically wounded, authorities said.
Dzhokhar Tsarnaev somehow slipped away. He ran over his already wounded brother as he fled by car, according to two law enforcement officials who spoke on condition of anonymity because they were not authorized to discuss the investigation.
Tamerlan Tsarnaev died at a Boston hospital after suffering what doctors said were multiple gunshot wounds and a possible blast injury.
The brothers had built an arsenal of pipe bombs, grenades and improvised explosive devices and used some of the weapons in trying to make their getaway, said Rep. Dutch Ruppersberger, D-Md., a member of the House Intelligence Committee.
Another uncle, Alvi Tsarnaev, who also lives in Montgomery Village, Md., told news organizations that Tamerlan Tsarnaev had called him Thursday night — hours before his firefight with police — and the two spoke for the first time in two or three years. He said the young man asked for forgiveness for the rift in the family.
"He said, 'I love you and forgive me,'" the uncle said.
Watertown resident Kayla Dipaolo said she was woken up overnight by gunfire and a large explosion that sounded "like it was right next to my head ... and shook the whole house." She said she was looking at the front door when a bullet came through the side paneling. SWAT team officers were running all over her yard, she said.