A Baltimore City police officer shot and killed a firefighter and his girlfriend early Sunday morning, before turning the gun on himself, according to Anne Arundel County police.

The suspected murder-suicide — which police said stemmed from a love triangle — disturbed many on the suburban Glen Burnie street where firefighter Andrew Scott Hoffman, 27, lived, and sent the Baltimore Fire Department into mourning.

"That was my best friend," said an emotional Fred Scheper, 29, of Pasadena, who came to the neighborhood after he heard of the shooting. "I've known him for 23 years. It's very shocking. He was a great guy. He saved people's lives every day."

Police say Baltimore Police Officer Christopher Lee Robinson, 37, of Abingdon, entered Hoffman's home armed with a gun, and shot the firefighter and his girlfriend, Marie Leanne Edith Hartman, 26, of Glen Burnie, around 1:35 a.m.

Hoffman, who grew up in the area and attended Glen Burnie High School, had recently begun dating Hartman, Scheper said.

"He was the happiest I've even seen him in his life in the past two months with the new girlfriend," he said.

Lt. T.J. Smith, a spokesman for the Anne Arundel police, said investigators probing the killings were "able to quickly determine this was a domestic-related murder-suicide."

"There is no public threat in this area. We don't have any outstanding suspects. We don't have any concerns for public safety," he said. "This is an absolute tragedy. Two young people in their twenties were the victims of this."

Dee Beatty, a family friend of Hartman's mother in Glen Burnie, said Hartman previously dated Robinson.

"She broke up with him and started dating the firefighter," she said.

Beatty said Hartman, who aspired to one day become a police officer, leaves behind a young son.

"Marie was an excellent mother," she said. "She was a beautiful girl. She was kind and caring and loving and she would help anybody."

Police said both Baltimore Police Commissioner Anthony Batts and Anne Arundel County Police Chief Kevin Davis responded to the scene.

Smith said officers were going door-to-door in the area, informing neighbors of the crime.

"It's a shock to the community," he said. "Our investigators are still working this case to determine what occurred that led to this situation."

Smith said county officials removed Hoffman's dog from the home.

Neighbor Phil Sperlein, 58, said he was awakened by commotion around 1:30 a.m. — when he saw a street full of police cars and officers "running around, yelling."

He described Hoffman has a "nice kid," who was "gregarious" and used to have friends over to play horseshoes. He said Hartman had been over at the house a lot in recent weeks.

"It's sad to say, but the gun culture that we got nowadays, everybody wants to solve their problems at the end of a pipe," Sperlein said. "I've got a temper, so I know I shouldn't own a gun. ... It was all over a woman. I don't get it. I love my wife, but there ain't a woman in the world worth going to jail or dying over."

Fire Chief Jeffrey Segal issued a statement regarding Hoffman's death, noting he was a "third-generation member of the fire department" who had been with the city department since 2006.