WOONSOCKET, R.I. — Police in Rhode Island are trying to determine who brought several rounds of live ammunition that were discovered by a custodian in a middle school boys' restroom.

Woonsocket Middle School was put on lockdown Friday afternoon after the discovery.

The Providence Journal reports that a teenage girl said she saw a possible shooter but later recanted her story.

Woonsocket Police Chief Thomas F. Oates III says a custodian was checking the restroom shortly before school dismissal when she found small-caliber ammunition. She immediately brought it to the principal's office.

Around the same time, the 14-year-old girl was overheard by a teacher saying she saw someone on a footbridge reaching into a backpack, which ultimately prompted the lockdown. Most students had already left the school as police conducted a room-by-room search.