Baltimore County Police are investigating after a gun was found on Sparrows Point High School grounds Friday afternoon.

A student protest of U.S. Immigration and Customs Enforcement had ended when officers responded to reports a firearm was found outside the building, according to county police. The school system had dismissed students two hours early ahead of inclement weather.

Detectives determined a relative of a student accidentally dropped the firearm while picking up the child from school after the walkout, police said. The investigation is ongoing.

Leadership at Sparrows Point middle and high schools sent an email to families Saturday morning. Administrators said the firearm was not brought into the school building.

“We appreciate the quick actions of those who reported the situation and the prompt response from law enforcement,” principals Eric Eiswert and Larissa Santos wrote. “We continue to remind students and families to report any concerns to school staff or the police so they can be addressed promptly.”

This week, a 7-year-old boy was hospitalized with a gunshot wound after a firearm was discharged in an Anne Arundel County elementary school. Eashan John Stefanski, 34, of Pasadena, was charged with allowing a minor access to a firearm in connection with the accidental shooting.

This article may be updated.