(Gresham, OR)  --  Four people are under arrest in connection with a Monday night murder in Gresham.  People reported hearing a gunshot and police were called to North Gresham Grade School around 11:20 at night.  A man's body was found in a parked car at the school.  Andrew McMahon of Gresham, Austin Brown of Portland, and two 17-year-olds from Gresham were arrested and charged with murder and robbery.