A school bus carrying 18 students apparently hit a patch of ice Monday morning, crashed into parked cars and then careened toward a post office, nearly striking the building.

The bus was on the 1400 block of E. Minnehaha Avenue near Birmingham Street around 8 a.m., when the crash occurred, said St. Paul Police Department spokesman Steve Linders.

The bus, carrying 18 kindergarten through fifth-grade students and an adult bus monitor, was en route to West Side Summit Charter School and had one last pick up to make that morning. Karen Klinzing, the school’s executive director, said that the bus apparently hit a patch of ice.

Police have said the cause of the crash is under investigation, and that drugs and alcohol do not appear to be factors. The driver was cooperative with investigators.

An 8 and 10-year-old on the bus and the adult bus monitor were transported to a hospital for “precautionary” reasons, Linders said. They complained of aches and pain, but did not sustain serious injuries. Klinzing said they were all discharged later Monday, and were at home recuperating.

The school alerted parents, a few of whom took their children home after the crash. The remaining students were interviewed and checked by a school nurse, Klinzing said.

“Our primary concern is the wellness of the children and staff here today,” she said.

The bus was traveling westbound on Minnehaha Avenue when it sideswiped three cars, jumped a curb and careened toward the post office building. Linders said the bus stopped short of striking the building, it’s left front tire breaking off and coming to rest under the bus.

The intersection is a two-way stop, with stop signs for vehicles traveling north and south on Birmingham, according to Linders.

The bus is owned by the northeast Minneapolis company, Bille Bus Transportation, which did not return multiple messages Monday.

Klinzing said the school contracts with the company for six routes in the morning and six routes in the afternoon. She said that the school spoke to the company about a month ago regarding the driver who was involved in Monday’s crash.

Klinzing said the bus driver wasn’t getting to school on time, so the school talked to the company about his “being attentive at the wheel.” A coach rode the route and monitored the driver at one point, she said.

Bille Bus will continue to serve the school, she said, with a new driver at the wheel of Monday’s route for the foreseeable future.

The company provides bus, van and medical transportation to hundreds of clients in the Twin Cities and surrounding suburbs, according to its website.

It also serves public schools, charter schools, and private schools.

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