Columbus police are investigating a rash of shootings over the long holiday weekend that left two men dead and two injured. Authorities say they found an unidentified 21-year-old man shot to death around 3:15 p.m. Friday. He was lying in the middle of the street near Windsor Avenue and Wentworth Road. A motive is being sought. At about 4:15 a.m. Saturday, 25-year-old Mikal J. Kirkland died of gunshot wounds near Kimball Place and East Fulton Street. A second unidentified victim in that shooting was transported to a local hospital. He was listed in critical condition. Police report Ahman Suliman, a 20-year-old clerk at a store on Courtright Road, was shot around 5 p.m. Friday as he broke up a fight in the parking lot. He was reported in stable condition.