LANCASTER, Pa. (AP) — Classes have been dismissed early at a central Pennsylvania school where a single bullet was discovered in the building.

Officials say they didn’t find a weapon at Manheim Township High School on Friday.

According to a district statement, the school was placed on lockdown Friday morning after the bullet was found on the floor of a classroom.

Administrators say they worked with police to investigate, including searching the room and interviewing students.

Officials determined there was no immediate threat, but still don’t know where the bullet came from.

Students were released at 12:30 p.m.

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