STONEHAM, Mass. (AP) – A car with an elderly man behind the wheel hopped the curb outside an elementary school as class was letting out Friday, pinning children and adults against a concrete wall and injuring 12 people, at least four of them seriously, authorities said.

The crash happened shortly before 3 p.m., as students from Central Elementary School in this Boston suburb were being picked up by their parents.

Police Chief Gregory O’Keefe said described a chaotic scene. “At any scene like this it’s total panic – children screaming,” he said.

The name of the driver was not immediately released. O’Keefe said he did not know the relationship between the driver and the student he picked up, who was in the car at the time of the crash. He said speed, drugs or alcohol did not appear to be factors.

Three children – two 3-year-olds and a 5-year-old – and an adult woman were taken to Massachusetts General Hospital in Boston. The adult and the 5-year-old were in serious condition Friday, the two younger children were in fair condition, a hospital spokeswoman said.

The hospital’s chief of emergency medicine, Dr. Alasdair K. Conn, said the 5-year-old had severe leg injuries, and it was not certain that the child’s legs could be saved. The woman underwent surgery with “a severe leg injury and vascular injuries.”

Four others – three adults and one child – were taken to nearby Winchester Hospital, where they were treated in the emergency room for non-life-threatening injuries and were expected to be released, hospital spokeswoman Marit Davies said.

Melissa McPherson, a spokeswoman for Tufts New England Medical Center, said that a 6-year-old boy was also admitted to NEMC’s Floating Hospital for Children in critical condition. Conn said he knew of another child who was being treated across town at New England Medical Center.

It was not immediately clear whether the other victims were hospitalized for their injuries.

The badly damaged car was removed from the sidewalk at the school’s entrance about 21/2 hours after the accident. A disabled driver placard hung from the rearview mirror. A child’s blue backpack was pinned underneath the front end of the blue Chevrolet sedan. Papers and other debris were strewn about the sidewalk and the adjacent 3-foot-high cement wall.

“It appears to just be a tragic accident,” said Dr. Joseph Connelly, Stoneham’s schools superintendent.

A state police accident reconstruction team was on the scene, O’Keefe said.

The school has about 450 students. Stoneham is about 10 miles north of Boston.