FLINT, Mich. (AP) — A charter school in Flint is closed for the day after a bullet struck a public transit bus carrying students.

The Flint Journal reports Friday’s closure of Madison Academy comes after authorities say a gunshot broke a rear window on a Mass Transportation Authority bus Thursday afternoon on the city’s southeast side.

The newspaper says more than 30 children were aboard. No injuries were reported.

School officials say the shutdown is to ensure the safety of students and to allow authorities time to investigate.

Flint resident Rebekah Fitch had four children on the bus, including two sitting near where the bullet struck after traveling through the window. She says she was terrified when she got a call from one of her children telling her about the shooting.