Two officers are shot and critically injured in the US city of Boston in an ambush attack by a heavily armed gunman wearing a ballistic vest.

Boston Police Commissioner William Evans told reporters during a press conference early on Thursday that the incident happened on Wednesday night inside an apartment on the city’s east side.

“We had two officer gravely injured there and we had no choice,” he said. “Let’s just hope they pull through.”

Officers were responding to a domestic dispute between two roommates when a man armed with an assault rifle and a protective vest started shooting at them.

The suspect continued firing at officers from an apartment for several minutes, but he was finally shot and killed by other responding officers.

The injured cops are in critical condition. They were taken to Massachusetts General Hospital where they were likely to undergo surgery.

“Please pray for our officers,” the Boston Police Department tweeted after the shooting.

The motive for the shooting and identities of the wounded officers are not yet known.

In another confrontation, one police officer was shot and wounded in Baltimore, Maryland.

He was reportedly recovering in a hospital. Police were searching for three suspects.

The incidents are the latest in a string of fatal shootings of law enforcement officers across America amid an outcry over the deaths of unarmed African Americans at the hands of police.