BALTIMORE — Two people died and a veteran police sergeant was seriously wounded after a man with a gun entered a Baltimore methadone clinic and opened fire, officials said.

Officers who arrived at the clinic Monday morning tried to “de-escalate the situation many times” before the armed man shot at police and officers returned fire, killing the gunman, Baltimore Police Commissioner Michael Harrison said.

The gunman, whom police have not identified, went into the clinic to get methadone, and the situation “escalated,” with people inside reporting that the man fired at least two shots about 7 a.m., Harrison said. The motive for the shooting is under investigation, he said.

When officers arrived at the clinic, they tried to calm the man, but he began firing at them, striking Sgt. Bill Shiflett, Harrison said. Shiflett, a 25-year veteran of the force, was dragged from the building to safety by a fellow officer.

Officers shot the gunman, who later died at Maryland Shock Trauma.

Shiflett, 48, who was shot in the stomach underneath his bulletproof vest, was also taken to Shock Trauma, where he was in stable condition, hospital officials said.

While officers were searching the clinic, they found another man in a different room suffering from gunshot wounds. He was taken to a hospital, where he died, and any connection he may have had to the clinic was not immediately clear.

A woman who worked at the clinic suffered injuries that were not considered to be life-threatening. Officials did not say how she was injured.

Harrison said officers responded to the Man Alive Lane Treatment Center, in the 2100 block of Maryland Avenue, as an “active-shooter scenario.”

“This was a dangerous situation that could have been far worse for our officers,” Harrison said. “They showed extreme courage, extreme bravery and extreme professionalism.”

Police found a gun near the attacker’s body, and the incident was captured on police-worn body camera, Harrison said.

Harrison said a young officer with 2½ years on the force pulled the sergeant to safety.

“This morning, a senseless act of violence in Baltimore City took the life of a civilian and injured a police officer,” Gov. Larry Hogan (R) said in a tweet. “Our hearts are with the victims’ loved ones, and we are grateful for the prompt response by law enforcement.”

Anthony Ambridge, a former Baltimore City Council member who was on the board of the Man Alive Lane Treatment Center for more than 30 years, said he spoke Monday afternoon with the organization’s executive director about the shooting. Ambridge said the employees were devastated.

“It is a dedicated group of professionals servicing the community,” he said.

An official with Man Alive could not be reached for comment. A telephone message for the clinic’s main number said it would be closed Tuesday and directed clients to a nearby clinic for services.

The message also directed patients “in need of ­trauma-
response services related to Monday’s incident” to a number for 24-hour crisis response assistance.

Man Alive is one of several clinics in the neighborhood, but it has a deep history as the first methadone clinic to open in the state and the second to open in the country, Ambridge said.

Man Alive was founded in the 1960s and originally operated on Charles Street before moving to its current location about 12 years ago, Ambridge said.

George Dowler was in the clinic waiting for his daily treatment when he heard gunfire, according to the account he gave to the Baltimore Sun. Dowler told the newspaper that he then saw another patient holding an employee at gunpoint, threatening to shoot her and demanding access to medication behind a counter. Pippy Scott, a woman inside the clinic, described a similar scene to the Sun, saying she saw a man aiming a gun at a woman’s head after yelling for methadone.

Police taped off the block and the entrance of the clinic, which is on a quiet, tree-lined West Baltimore street alongside apartments, a Chinese restaurant and a church.

Methadone patients tried to cross the yellow tape but were stopped by an officer.

“I’m trying to get my treatment,” one man said, as he attempted to get into the nondescript brick building with a tan awning.

“You’ve got to go to the alley,” the officer said.

“I don’t know where to go,” the man said.

In the alley, an ambulance sat at the back of a dining hall where some clients go for free meals.

Angela Savage is a client at the Reach Clinic across the street. She rushed to the scene after hearing about the injuries. When she arrived, she said, she saw a nurse run out and “a lot of chaos.”

Theresa Lingebach, 29, and Jamie Greeley, 56, sat on a stoop around the corner from Man Alive, where they have been getting treatment for the past four years.

Neither was in the clinic at the time of the shooting but they were trying to piece together what might have happened.

The women said that there is no buzzer or security system to enter the clinic but that there are two guards posted inside and outside the facility.

Lingebach said the clinic was beefing up security.

“They were just adding extra cameras on Thursday or Friday,” she said.

The building has several floors where counselors work. The first floor has the methadone, they said.

Many who rely on the clinic have also come to care about its employees, the women said.

Lingebach said her counselor is like her father.

“It’s just sad,” she said. “They are doing a service to the community.”

Julie Tate contributed to this report.