A United Airlines flight bound for Spain from Newark Liberty International Airport turned around mid-flight on Saturday due to a possible security threat.

The flight departed at around 6pm local time for Palma de Mallorca, Spain, but landed back at Newark at 9.37pm, according to the Port Authority of New York and New Jersey.

The airline said there were 190 passengers and 12 crew members on the Boeing 767 aircraft.

According to air traffic control audio, security came to inspect the aircraft after someone named their Bluetooth device a “certain four-letter word”. Aviation news outlet AirLive later identified the word as “BOMB”.

A passenger posting on social media said crew members repeatedly asked passengers to turn off all Bluetooth devices but two devices remained on.

The flight turned around after communicating with the airline’s headquarters in Chicago.