MBTA officer who lost all blood in shootout with bombing suspects is expected to recover

The Massachusetts transit officer who was shot while responding to Friday's shooting that killed a Massachusetts Institute of Technology police officer—and sparked the citywide manhunt for the Boston Marathon bombing suspects—went into cardiac arrest and lost his entire blood supply but is expected to recover, doctors say.

Richard Donohue Jr., a 33-year-old member of the Massachusetts Bay Transportation Authority, was shot in the right thigh during a shootout with the suspects in Cambridge, Mass., late Friday. A bullet severed Donahue's femoral vein and artery, Dr. David Miller, a critical care physician at Mount Auburn Hospital, said on Sunday, and he began to "bleed out."

He went into cardiac arrest at the scene, and it took doctors 45 minutes to fully revive him, the hospital said.

“CPR was started in the field, and he required a prolonged resuscitation that started at the scene ...,” Miller said. “He continues to need high levels of sedation.""

Sean Collier, the 26-year-old MIT police officer, was killed before Donohue arrived.

Doctors performed blood transfusions to replace Donohue's blood and were able to save his leg, Miller added.

The officer, from Woburn, Mass., remains in intensive care in critical but stable condition.

“He loves being a cop," Edward Donohue, Richard’s younger brother and a Winchester, Mass., police officer, told the Los Angeles Times. "We were just talking the week before about how much he loves the job."

Dzhokhar Tsarnaev, the surviving bombing suspect, remains in serious condition at Beth Israel Deaconess Medical Center, the FBI said Monday. The 19-year-old, who is on a ventilator and cannot speak, was said to be "responding sporadically in writing" to questions from authorities late Sunday.