Three men were killed and one man was seriously injured in Poolesville yesterday evening when the car in which they were riding crashed into a tree, Montgomery County police said.

The injured man, who was thrown from the vehicle, was airlifted to Maryland Shock Trauma Center, Officer Louise Marthens said.

The cause of the crash -- which occurred about 6:45 p.m. on Route 28, a half-mile east of Bucklodge Road -- was under investigation.

Police last night had not yet identified the victims.