(CNN) -- Homicide detectives outside Baltimore are investigating an apparent murder-suicide involving a police officer and a firefighter.
Three people were found dead inside a home in Glen Burnie, Maryland, early Sunday morning after a reported shooting around 1:35 a.m., police in Anne Arundel County said.
Police said the suspected shooter -- Christopher Lee Robinson, 37, a Baltimore police officer -- was one of the people found dead at the scene.
Baltimore firefighter Andrew Scott Hoffman, 27, and Marie Leanne Edith Hartman, 26, were killed.
"Preliminary investigation indicates that the suspect/shooter was one of the deceased and that he had a relationship with the female victim," police said.
Police said they were still investigating the shooter's motive, but described the shooting as a "domestic incident."
"It's a tragic situation. ... We believe this incident is all connected to some known relationships," Anne Arundel County police spokesman Lt. T.J. Smith told CNN affiliate WBFF.
Hoffman was a third-generation member of the fire department who had worked for the city since 2006, Baltimore Fire Chief Jeffrey Segal said in a statement, according to WBFF.
Earlier this year, WBFF said, he earned praise from local officials for helping a lost toddler find his way home.
CNN's Rick Martin contributed to this report.