Police have arrested four people on suspicion of murder and robbery in the death of a 24-year-old Troutdale man.

Police said the dead man was found shot in a car crashed into a side of North Gresham Elementary School. Austin Brown of Portland, 20; Andrew McMahon of Gresham, 21; a 17-year-old Gresham boy; and a 17-year-old Gresham girl have been arrested on suspicion of first-degree murder and robbery.

Police were called to the area about 11:20 p.m. Monday on a report of a gunshot heard, Gresham police said in a news release. The man was dead by the time officers arrived.

An autopsy will be performed to determine the man's cause of death, police said. His identity has not yet been released, and police said the East County Major Crimes Team has been investigating the circumstances of his death.

The Gresham-Barlow School District said the elementary school would be closed Tuesday. The last day of school is Thursday.

Brown and McMahon are being held without bail in the Multnomah County Detention Center, records show.

Police ask anyone who saw or heard anything unusual near the school to call 503-618-2719.

-- Everton Bailey Jr.

ebailey@oregonian.com

503-221-8343; @EvertonBailey

Jim Ryan of The Oregonian/OregonLive staff contributed to this report