Two students and an adult were killed Tuesday afternoon when a pair of school buses collided on a Tennessee highway.

KNOXVILLE, Tenn. — Two buses bringing children home from school collided on a Tennessee highway Tuesday afternoon, killing two students and an adult and injuring another 27 people.

Police said a preliminary investigation indicated one bus made a sharp left turn, crossed over a concrete median and hit the second bus, which was traveling in the opposite direction. The second bus flipped onto its side and slid.

The children killed were in third grade or below, said Knoxville Police Chief David Rausch. The adult who died was an aide.

Three seriously injured people were taken to the University of Tennessee Medical Center and were in stable condition, Rausch said. Medical Center spokesman Jim Ragonese said a total of seven people were treated there, and three of them had been discharged by Tuesday evening.

East Tennessee Children’s Hospital spokesman Erica Estep said another 20 children were being treated there for injuries that were not life-threatening.

Rausch said 18 of the 20 had been on a bus going home from Sunnyview Primary School, which serves kindergarten through second grade. The other bus involved in the crash was from Chilhowee Intermediate School, which serves third through fifth grade.

Class was not being held at the two schools Wednesday, but counselors were being made available.