Two students and a teacher’s aide were killed after school buses collided in Knoxville, Tennessee on Tuesday.

NBC News reported that the accident, which occurred on wet roadway around 2:50 p.m. EST, also injured more than 20 others from two different schools. While most of the passengers were treated for minor injuries and discharged, two children and one adult were transported to the University of Tennessee Medical Center and listed in stable condition.

Authorities said all of the children were between kindergarten and third grade.

The Knoxville News Sentinel noted that aide Kim Riddle was among those killed when one of the buses made a sharp turn, crossed over a median and hit the second bus.

“She was one of our youth ministers. It was her dream to work with children and to work in Knox County. She got that dream when school opened up,” said Mt. Calvary Baptist Church Senior Pastor Leroy Franklin.

An investigation into the accident is ongoing.

Classes at the schools were not held on Wednesday.