The resident manager of a Gaithersburg apartment house and a tenant in the building were shot and fatally wounded inside the building last night in an incident that Montgomery County police said apparently followed a dispute with their assailants.

Police said they were questioning two suspects early this morning in connection with the shootings, which took place about 10 p.m. on an upper floor of the four-story building at 49 W. Diamond Ave. No charges had been filed as of 1 a.m. today.

Both victims staggered down a staircase and out of the building before collapsing on a grassy plot near the rear door, according to police.

The resident manager, identified as John Offutt, 26, was shot in the head and taken to the shock-trauma unit at Suburban Hospital where he died at 12:24 a.m.

The other man, identified as Michael R. Cashion, 25, was shot twice in the chest, and died at 11:41 p.m. at Shady Grove Adventist Hospital.

Both were shot with a handgun, according to Sgt. Harry Geehreng, a county police spokesman. He said police believed that the shootings followed an argument and that the victims knew their assailants. Details of the dispute were unclear, he said.

One resident of the area reported hearing a man shout: "Oh no, don't," shortly before hearing four or five gunshots. Several neighbors said they found the two victims lying behind the building shortly afterward. They said one of them was moaning and calling for help.

Police, using three dogs, searched the area around the building for at least an hour and a half after the shootings.