A mother whose 12-year-old son was among four children killed in a school bus crash asked parents to give their kids an extra hug as this small Minnesota town prepares for a memorial service to mourn the victims.

Gov. Tim Pawlenty planned to attend the service Thursday night in the Lakeview School's gymnasium, and locals expected most of Cottonwood's 1,150 residents to be there.

Superintendent Sheldon Johnson told reporters that former teacher Kandy Stevens, whose son was among those killed, had asked him to read a statement.

"She wants people to know that Reed was a young man who loved God, his country and his family," Johnson said. "We know that he is with the Lord, and we ask all parents to give their kids an extra hug tonight and every night."

The National Transportation Safety Board and the Minnesota State Patrol are investigating Tuesday's crash, which occurred when a school bus collided with a van, then rolled onto a pickup.

Among those killed were two brothers, Jesse Javens, 13, and Hunter Javens, 9, as well as Reed Stevens, 12, and Emilee Olson, 9. At least 14 other people were hurt.

The van had been heading east on County Road 24, which has a stop sign as it ends in a T intersection with state Highway 23, the road the bus was traveling.

The State Patrol would not confirm several media reports that the driver of the van, 23-year-old Alianiss N. Morales of Minneota, lacked a valid driver's license. The Marshall Independent, citing court records, reported Morales pleaded guilty in Chippewa County in 2006 to driving without a valid license.

Classes were scheduled to resume Thursday at Lakeview School, a 585-student K-12 school 140 miles west of Minneapolis, which was reeling from the tragedy. Parents and students streamed into the building Wednesday for a meeting.

"It's terrible for the families," said Heidi Klocow, the mother of a third grader. "We knew a lot of people on that bus."

Mary Taylor, who attended the meeting with her 17-year-old son Miles, said she was struck by "the utter silence" when she first entered the building.

"No one knows what to do or say," she said.

Charlie Olson, Emilee's father, said two of his sons also were injured in the crash, but they are expected to be fine. "Yesterday God got four angels and he's not getting any more," he told KSTP-TV. "That's it."