OAKDALE, Minn. — Police in a Twin Cities suburb looked for additional evidence Tuesday in an apparent random shooting that left a 9-year-old boy dead and his mother and another woman wounded.

Detectives combed a 6-block area for spent gun casings and additional gunfire damage from the shooting Monday evening in Oakdale, according to police spokeswoman Michelle Stark.

Police say a 34-year-old Oakdale man opened fire randomly at passing vehicles near a Rainbow Foods store about 6:10 p.m. Monday. The boy and his 39-year-old mother were struck in one vehicle. A 68-year-old woman in another vehicle was shot in the hand, according to the police report. All were taken to Regions Hospital. Stark says the boy died of his injuries. The women are expected to recover.

The suspect was arrested several blocks away. Police say a handgun and ammunition were recovered.

Several vehicles were impounded by police as the investigation continued, Stark said.

Investigators believe the gunman acted alone. The suspect was taken to the Washington County Jail in Stillwater where he’s being held on possible charges of second-degree murder and first-degree assault, the police report said.

The state Bureau of Criminal Apprehension was joining the investigation, Starks said.