MOORE, Okla. (AP) — The principal of the Oklahoma elementary school where seven children died in a tornado said her teachers did everything they could to save their lives.

The twister hit just before the end of the school day on Monday. The school had spent the first half of the day celebrating the students’ accomplishments during the year.

Simpson said some teachers took the weight of collapsed walls onto their bodies to save children.

Monday’s tornado was a top-of-the-scale EF5. The storm killed 24 people, including 10 children.

Principal recounts storm hitting school