HANOVER, Pa. (AP) — Nearly 40 students and staffers at a charter school complex in eastern Pennsylvania were taken to hospitals Friday for evaluation after several people reported not feeling well, but authorities said it was not immediately clear what may have caused the issue.

Emergency responders went to the Lehigh Valley Academy Regional Charter School in Hanover around noon, after school officials reported nearly a dozen people inside one of three buildings there were ailing.

The building, which houses seventh through twelfth grade students, was evacuated “out of an abundance of caution,” but normal operations continued at the other buildings, where younger students are taught.

Authorities did not disclose details on the symptoms the ill people were dealing with, and it wasn’t immediately clear if anyone had suffered serious injuries.

The charter school has 1,825 students who come from 16 school districts in the area.