CHICAGO (AP) — A cross-country United Airlines flight was forced to land in Chicago Wednesday as a result of what local media reports, citing a preliminary police report, called a bomb threat.

United said only that flight 1533 from Newark to Los Angeles landed safely at O'Hare Airport as the result of a “security issue." It declined further comment on the incident.

Television footage aired by Chicago stations showed the plane landed at O'Hare away from the terminal, flanked by black vans. An unidentified passenger interviewed on local television said the flight crew announced the diversion about two hours into the flight without explanation, after which passengers were confined to their seats.

After the plane landed, that passenger said, they were informed that someone had written a bomb threat on a mirror in one of the plane's lavatories. Passengers were then required to leave the plane without their belongings, he added. Another unnamed passenger said in a television interview that carry-on luggage was removed from the aircraft by law enforcement and searched.

Police met the flight and “cleared the scene,” according to the Chicago Police Department, which referred questions to the FBI. An FBI spokesperson confirmed that the bureau and law enforcement partners responded to an incident concerning an aircraft at O'Hare Airport but offered no further information.

"There is no indication that there is an imminent threat to public safety or the facility itself at this time,” the spokesperson added.

United said the flight resumed its planned trip to Los Angeles later Wednesday afternoon.