A suspect and another man were killed and a Baltimore police officer was injured Monday morning in a shooting at a methadone clinic.

Baltimore Police Commissioner Michael Harrison said the shooting was reported at 7:09 a.m. at the Man Alive methadone clinic in the 2100 block of Maryland Avenue. Police received a call for an armed person.

Harrison said the officers tried to de-escalate the situation, but the suspect began shooting at the officers.

"As the suspect fired upon our officer, he returned gunfire but was struck by the suspect's rounds," Harrison said.

Baltimore police Sgt. Bill Shiflett, a 25-year veteran assigned to the Northern District, was shot in his lower abdomen under his bulletproof vest. Shock Trauma officials said Shiflett underwent surgery and was being taken to the intensive care unit.

Harrison said the suspect and another man found in a separate room suffering from gunshot wounds were taken to a hospital, where they died.

"We only fired at one suspect," Harrison said. "We only encountered one suspect who fired at our officer and we only fired in one direction at one person."

Harrison said an employee of the clinic was also injured during this incident.

"She was transported to a hospital, and her injuries, at this time, are not believed to be life-threatening," Harrison said.

A patient told the I-Team that a man came into the clinic and demanded a large container of methadone.

"Preliminary indication is that he went in to get methadone," Harrison said.

The patient said the man held a gun to the head of a staff member.

"He had the woman by the head and had the gun in her head, and everybody was afraid. She was a nurse," a patient told 11 News.

Police said a firearm was recovered at the scene.

"We recovered what we believe to be the suspect's gun on the scene near his body," Harrison said.

Harrison praised a young officer whom he said put his life in danger when he pulled Shiflett, his supervisor, to safety after Shiflett was shot.

"This was a dangerous situation that could have been far worse for our officers. They showed extreme courage, extreme bravery and extreme professionalism, all of which was captured on bodycam video," Harrison said.

Police body-worn camera has been reviewed.

Maryland Avenue is closed between 23rd Street and North Avenue, WBAL NewsRadio 1090 AM's Jim Russ reported.