MOSCOW, Idaho (AP) — University of Idaho officials say four people were injured in an explosion that happened in a parking lot where people had gathered to test an experimental rocket.

Officials said in a statement the explosion happened just before 10 p.m. on campus next to a steam plant.

Four people were taken to a local hospital for treatment. Officials say they didn't know the names of those injured.

Officials said there was no danger on campus after the incident.