CAMBRIDGE, Mass. — Doctors say the Boston transit police officer wounded in a shootout with the marathon bombing suspects had lost nearly all his blood and his heart had stopped from a single gunshot wound that severed three major blood vessels in his right thigh.

Surgeons at Mount Auburn Hospital in Cambridge say 33-year-old Richard Donohue is in stable but critical condition. He is sedated and on a breathing machine but opened his eyes, moved his hands and feet and squeezed his wife’s hand Sunday.

Emergency workers started CPR on the scene to restart his heart. Doctors say he is expected to make a full recovery and that nerves and muscles in his leg are intact.

Transit officials say Donohue had gotten out of his cruiser and was shooting at the suspects when he was hit late Thursday night in a gunbattle in Cambridge.

“He went in there and engaged people who were shooting at his fellow officers,” Donohue’s brother, Edward, said at a news conference Sunday at the hospital. “I cannot describe the pride I have,” said the younger Donohue, who is a patrolman for the Winchester Police Department.

The fellow officers included a friend, MIT police officer Sean Collier, who died in the shootout.

Richard Donohue has been a transit officer for three years, said Paul MacMillan, chief of the Massachusetts Bay Transportation Authority.

The bullet wound did not injure bone but severed the femoral vein and both branches of the femoral artery in Richard Donohue’s right thigh, doctors said.

“The officer’s blood volume was almost entirely lost to the point of the heart stopping,” said Dr. Russell Nauta, chairman of surgery at Mount Auburn. It was a 45-minute effort to get it beating again, he said.

Doctors say Donohue’s prognosis is good, and family members expect his sense of humor to return.

“His wife said: ‘We’ll never live this down. He’ll never have to make himself another sandwich,'” the brother said.

Richard Donohue’s wife, Kim; 6-month-old son, Reggie; father; sister; grandmother; and others were with him at the hospital.