Law enforcement officials are investigating how a stun gun ended up on a JetBlue aircraft in New Jersey Friday night.

A crewmember on the airline found the stun gun in a seatback pocket while cleaning Flight 1179 after it landed at Newark Liberty International Airport at around 10 p.m., JetBlue spokesman Sebastian White said in a statement.

The plane, carrying 100 passengers and crew arrived at the New Jersey airport on a flight from Boston.

The weapon was handed over to police from the Port Authority of New York and New Jersey, and the investigation was taken over by the FBI, the Transportation Security Administration said in a statement.

All current information indicates this is not part of an attack, said Special Agent Bryan Travers of the Newark Division of the FBI.  He added that the FBI has identified the passenger who was sitting in the seat that uses the pocket in question, but could not yet link that person to the stun gun definitively.

Officials at Massachusetts Port Authority, which owns and operates Logan International, had no comment on the incident.

Police described the gun as looking like a cell phone, a Port Authority spokesman said.  Cell phone stun guns are designed to closely resemble smartphones and are advertised as covert self-defense items.

It was unknown whether the device was sneaked past security, was placed on the plane after it landed, or belonged to a law-enforcement official, a U.S. source familiar with the investigation told Reuters, requesting anonymity.