The grisly week that began at the Boston Marathon Monday left one police officer dead.
As police closed in on the bombing suspects Thursday night, law enforcement officials say two officers were shot. One, transit police officer Richard Donohue, is in critical condition at Mount Auburn Hospital.
The other, Sean Collier of the MIT campus police, was pronounced dead Thursday night.
MIT says Collier had gone to respond to a report of an altercation on campus Thursday evening. Soon, word came over the police radio that he had been shot.