Two Boston police officers were shot in the Orient Heights neighborhood of East Boston late Wednesday night, and a suspect was shot dead at the scene, police said.

Police Commissioner William B. Evans said early Thursday that one officer was shot multiple times and was in critical condition at Massachusetts General Hospital. A second officer was shot once or twice and was in stable condition.

Both officers were listed in “extremely critical” condition and had undergone multiple blood transfusions, Evans said during an early morning press briefing outside the hospital.

The officers both suffered some “very serious wounds” and the medical staff is “going to watch them closely,” Evans said.

He said the violence erupted after police responded to a call for a domestic dispute possibly involving a gun between two male roommates at 136 Gladstone St. Multiple units responded, Evans said.

Once inside, Evans said, “We heard officers screaming on the radio 303,” which is code for shots fired. “The officers were screaming ‘officer down,’ “prompting more officers to rush inside, Evans said.

He said a suspect armed with an assault rifle and a ballistic vest fired at police, striking the two officers, and their fellow officers moved them to safety and returned fire, killing the heavily armed man.

Evans did not identify the deceased suspect or the wounded male officers. One officer has about 28 years of service, and the other one has been on the force for about a dozen years.

“I ask the public to pray for them,” Evans said. “All of the officers exhibited extreme courage and bravery.”

Mayor Martin J. Walsh noted that the shootings occurred hours after police had honored another officer who was killed in the line of duty in the 1970s.

“This job’s a tough job,” Walsh said of police work. “And oftentimes people don’t look at the other side of what happens with police officers.”

He said officials were praying for the injured officers’ health, and he also expressed support for the East Boston residents who were unnerved by the violence.

“It was shocking for the neighborhood,” Walsh said.

Suffolk District Attorney Daniel F. Conley said his office will investigate the police use of lethal force according to standard protocol.

“I ask the city and the region to please pray for them,” Conley said of the wounded officers.

In addition to the two officers who were shot, Evans said, nine additional officers were being treated at Tufts Medical Center for minor injuries sustained during the gun battle and for stress.

“Domestic calls … are probably the most volatile,” Evans said. “You never really know what you’re walking into.”

He said officers are “not proud when we have to use deadly force but obviously we had two officers gravely injured there and we had no choice. … Let’s just hope they pull through.”

Evans said the deceased suspect is in his early 30s. It was not clear if he had a prior arrest record.

The shootings sent the Orient Heights neighborhood into lockdown for a period late Wednesday.

Boston Police issued a shelter-in-place order for the area around Gladstone Street, but lifted it shortly after midnight, police reported on Twitter.

“Scene is secure. Residents kindly asked to remain inside,” police wrote.

Evans commended officers for their actions. “They moved in and neutralized the threat pretty quick that no one else got killed,” he told reporters at the scene in East Boston.

Multiple streets were blocked off near the crime scene early Thursday, as scores of Boston and State Police, SWAT units, and Transit and Winthrop Police scoured the area.

Bystanders were shocked by the shootings.

Marcus Ramirez of Lynn watched the police operation unfold from the corner of Bennington and Walley streets.

He said he heard reports of a shooting on social media while he was at his job at FedEx on McClellan Highway.

Travis Andersen/globe staff

Media waited for an early morning briefing outside Mass. General on two BPD officers shot in East Boston.

“I just saw cops driving fast by Suffolk Downs,” he said.

Lou Ristano, who lives in East Boston, said he could not get back to his home on Waldemar Avenue because police had blocked off surrounding roads.

“Obviously, something happened,” said Ristano. “I tried to drive home. Everything is blocked.”

Karen DeFelippo, who lives parallel to Gladstone Street, said she’s seen police walking up and down her street. She plans on keeping her family indoors for the rest of the night.

“Everybody is fine,” DeFelippo, 64, said. “We’re just staying inside because that’s what we were told to do.”

Joseph Armando of Revere said he was having dinner with friends at Great Chef Chinese Food in East Boston when he heard that officers were injured in a shooting.

“We came over here to see if everything is OK,” Armando said. “We were just really concerned about our community.”

The violence on Wednesday night in East Boston came two weeks after two undercover state troopers were fired at while they were conducting a gun-trafficking probe in Roslindale.

Neither trooper was hit in that case and two men have been charged in connection with the attack.

This story is developing and will be updated as information becomes available.

Listen to audio from the East Boston shooting

Cristela Guerra of the Globe Staff contributed to this report. Samantha J. Gross can be reached at samantha.gross@globe.com. Martha Schick can be reached at Martha.Schick@globe.com