A 200-pound pet chimpanzee in Stamford, Conn., Monday viciously mauled a woman he had known for years, leaving her critically injured with much of her face torn away, the authorities said. The animal was shot dead by the police after he assaulted an officer in his car.

The woman, Charla Nash, 55, a friend of the chimpanzee’s owner, was being treated at Stamford Hospital and might not survive, the authorities said.

“I’ve been doing this a long time and have never seen anything this dramatic on a living patient,” said the head of the paramedic crew that treated her, Capt. Bill Ackley of Stamford Emergency Medical Service.

The attack, in the driveway of a sprawling home in a densely wooded neighborhood on the north side of Stamford, also brought a brutal end to the life of the chimpanzee, Travis, 14, a popular figure in town who had appeared in television commercials and often posed for photographs at the towing shop operated by his owners. He had escaped before, and in 2003 playfully held up traffic at a busy intersection for several hours, but had no history of violence, the authorities said. Travis’s social skills included drinking wine from a stemmed glass, dressing and bathing himself and using a computer.