OAKDALE, Minn. (AP) — Police in a Twin Cities suburb were investigating an apparent random shooting that left a 9-year-old boy dead and his mother and another woman wounded, while a woman who witnessed the shooting said Tuesday that the suspected gunman appeared "nonchalant" as he walked calmly down the block, firing his weapon.

Police said Tuesday that a 34-year-old Oakdale man randomly fired at passing vehicles Monday evening in a neighborhood in this St. Paul suburb.

A boy riding in a vehicle with his mother was killed. His 39-year-old mother was injured. They were found in the parking lot of a nearby Rainbow Foods store, where they drove after the shooting. A 68-year-old woman in another vehicle was shot in the hand, according to the police report, and was found in another location. The women are expected to recover from their injuries.

The man was arrested several blocks away. He remained in custody Tuesday on suspicion of second-degree murder and first-degree assault. Police say they found a handgun and ammunition.

Cheryl Russell, 55, lives across the street from a house where the man told police he lived. She said she was sitting on her couch, which faces a bay window, about 6 p.m. Monday when she saw a short, stocky man in dark clothes walking down the street. Russell said the man seemed to be out for a stroll, but then began firing.

Russell said her son shouted from upstairs that a man was outside shooting at cars. Russell peered out the window while her husband called police. She heard about 15 shots, and could see flashes from the gun as the man fired it.

"He was nonchalant," Russell said. "Just walking like he was out for a stroll. It was crazy."

Russell said police were on the scene in minutes. She said she didn't know the gunman.

Detectives combed a six-block area for spent gun casings and additional gunfire damage, police spokeswoman Michelle Stark said. Several vehicles were impounded.

A small group of about 10 people huddled in prayer at the Rainbow Foods parking lot Tuesday to pray for the victims. The Rev. Chris Duckworth led the group, and read Psalms of Lament: "Psalms where the people are crying out, 'Why God? Why?'" Duckworth said.

Duckworth, a senior pastor at Grace Lutheran Church in St. Paul, invited friends on Facebook to join him to pray. He said he didn't know any of the victims, but knew he had to give people a chance to grieve.

"Frankly, I didn't know what else to do," he said.

The name of the boy was not immediately released, but he was a fourth-grader at Oakdale Elementary School, a school of about 500 students. A team of social workers and psychologists was talking with students Tuesday, said District 622 spokeswoman Jennifer McNeil.

McNeil said students are shaken up and "some of the kids are taking it pretty hard."

Washington County Attorney Pete Orput said authorities were still digging for information, and investigators planned to meet in his office Tuesday afternoon to review the case. He expected to bring charges Wednesday morning.

Copyright 2013 The Associated Press.