PHILADELPHIA (CBS) — Staff at a Philadelphia charter school found bullet holes and fragments in the cafeteria Thursday morning when they went to open it up to students, according to Philadelphia police. The department said staff arrived at Antonia Pantoja Charter School around 6:29 a.m.

That’s when they found five bullet holes in the cafeteria window. Officers also found two bullet fragments inside.

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Investigators said only one security camera facing 2nd Street was working at the time.

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No students were at the school when the shots were fired, officers said.

The incident is still under investigation.

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For a list of gun violence resources in Philadelphia, click here