Ammunition clip found on Southwest airliner.

The discovery of a loaded gun clip aboard a Southwest Airlines jet on Tuesday sparked a security scare at the Phoenix airport, until it was determined that the clip was left by a law enforcement officer, the airline said.

The clip containing bullets was found on the cabin floor by a passenger aboard Southwest Flight 1297 from Burbank, California, to Phoenix Sky Harbor airport, airline spokesman Paul Flanigan told Reuters by telephone.

The plane was met at the gate by local police and personnel of the federal Transportation Security Administration (TSA), Flanigan said.

After a brief investigation, authorities determined that the clip belonged to a law enforcement officer who apparently had dropped it during a previous flight on the same aircraft, according to Flanigan. A clip is the part of a gun where the bullets or cartridges are stored.