(CNN) — Four children were injured after a woman crashed her car through the window of a day care center classroom, according to Pennsylvania authorities.

The black BMW traveled all the way through one classroom of the Children of America Educational Childcare center before stopping at a back wall, the Bucks County Attorney’s Office said in a statement.

Four children were taken to the hospital, one of whom suffered serious injuries, the statement said.

“The driver of the vehicle sustained minor injuries, was treated and remains hospitalized,” it said.

The crash is under investigation, according to James O’Malley, the spokesperson for the district attorney’s office. He told CNN the woman was working as a delivery driver.

At the time of the crash — about 1:30 p.m. — there were about 17 children inside that room and about 79 total in the building .

All of the children have been accounted for and reunited with their families, the statement said.