LONDON (AP) — A 17-year-old boy has been arrested on suspicion of attempted murder after three people were assaulted with a sharp object at a secondary school in northern England, South Yorkshire Police said Wednesday.

Two adults and a child were treated for minor injuries but didn't need to be transported to a hospital, according to The Birley Academy.

The school, formerly known as Birley Community College, in the city of Sheffield, was closed for the rest of Wednesday.

The suspect was in custody.