Officials say one or two Braintree officers responding to a domestic disturbance on Liberty Street shot the man after he refused to drop a knife.

BRAINTREE - The Norfolk County district attorney's office says a man shot and killed by Braintree police Thursday morning was a 44-year-old former Quincy resident named Robert L. Dussourd.

Officials say Dussourd, who had recently been living on Liberty Street in Braintree, was shot by one or two Braintree police officers after he refused to drop a knife during a confrontation near his home around 3 a.m. Thursday. The district attorney's office said the two officers tried to subdue the man using non-lethal methods, including a beanbag gun, but he continued to brandish the knife and was shot.

District Attorney Michael Morrissey has promised a "full, deliberate and fair investigation" into the shooting. The district attorney said the officers immediately began life-saving measures while awaiting emergency medical workers, who took the man to South Shore Hospital.

Officials did not say when or where the man was pronounced dead.

Liberty Street resident Daniel Hoffman said he noticed lights outside his window around 2 a.m. and saw several police cruisers, ambulances and fire trucks. At one point, he said he heard two bangs, one after another.

"I knew it was gunshots," he said. "It had to be." Morrissey said Braintree police had been "cooperative" in the investigation, which is still in the early stages.

"While we are a long way from being done with this investigation, it is important in the case of a police shooting to provide information to the public, even if that information is preliminary in nature," Morrissey said in a statement. "Every police shooting demands a full, deliberate and fair investigation and that is what we are doing here."

Braintree Police Chief Russell Jenkins referred all questions to the district attorney's office.

Officials said the confrontation on Liberty Street started with a call around 1:20 a.m. for a domestic disturbance at a home near the intersection of Liberty and East Division streets, which marks the line between Braintree and Holbrook. Police were told that a man who lived in the home had left after brandishing a knife.

Police said officers using a dog were able to find the man hiding under a car parked outside the home. Police said the climbed out from under the car and confronted the officers while brandishing the knife.

Dussourd, a former resident of Cherry and Summer streets in Quincy, had several run-ins with police while living in the city in the 1990s and spent at least a year in jail, according to court records. In July 1997 he was arrested for assaulting two people and later given a one-month jail sentence. While out on probation the following November, he was arrested again for assaulting a woman with a hammer and was eventually sentenced to a year in jail.