(AP) - Authorities say roughly two dozen students were exposed to pepper spray at a northern New Jersey school when an 8-year-old girl inadvertently sprayed the substance.

The exposure at the Whitney M. Young Jr. Community School in Jersey City occurred around 10:30 a.m. Wednesday, spurring an evacuation that lasted for nearly two hours.

Officials say at least 19 of the affected students were treated at hospitals for minor issues and later released.

City Public Safety Director James Shea said the 8-year-old girl had a small pepper spray container on her key chain and inadvertently sprayed it, but further details were not disclosed.

Students and staff were allowed to return to the school around 12:15 p.m.

The incident remains under investigation.