DARBY, Pa. (CBS) — The discovery of a gun inside of a school in Delaware County prompted a lockdown on Thursday, officials say.

William Penn School District Superintendent Jane Harbert says there was a fight Wednesday that happened off campus, but it was brought into Penn Wood Middle School today.

Darby Police were called to the scene once the gun was found.

Authorities searched the school and an arrest was made.

There were no reported injuries and the school is back to normal operating order.

Officials say security will be ramped up during school dismissal.