CNN  — 

Doctors said Sunday that they are “cautiously optimistic” that a Massachusetts transit officer wounded in a shootout with the alleged Boston Marathon bombers will recover.

Richard H. Donohue, 33, is in critical condition at Mount Auburn Hospital in Cambridge, said Dr. Russell J. Nauta, a surgeon who operated on Donohue.

When the officer arrived at the hospital, his “blood volume was almost entirely lost to the point of the heart stopping” and first responders and emergency room staff helped restore Donohue’s pulse.