Portland police believe that a York County man who was found unresponsive outside a Gilman Street apartment building Thursday morning died of a drug overdose.

Police late Friday afternoon identified the victim as Marcus Reed, 46, of North Waterboro. He was in an apartment at 16 Gilman St., when he apparently overdosed, police said. The people he was with tried to take him to a hospital themselves, and got him down as far as the street, but called 911 when they could not get him into a car, police said. Emergency medical technicians responded and worked to save the man, but he was pronounced dead at the scene, said Lt. Robert Martin.

The public should call 911 immediately when they encounter someone who may be overdosing, Martin said.

“A person’s condition can change rapidly and the difference between life and death can be minutes,” Martin said.

The emergency call not only kicks off the ambulance response, but it also allows the dispatcher to give the caller potentially life-saving instructions on what to do until the ambulance arrives, Martin said. “Knowing what to do in the event of an overdose can be the difference between life and death.”

Gilman Street is near Maine Medical Center in Portland’s West End.

The cause and manner of death will be verified by the state medical examiner’s office, which is performing toxicology tests, Martin said.

Staff Writer Penelope Overton contributed to this report.