Bomb Threat Found in Bathroom Grounds United Flight in Vermont for Hours Officials confirmed nothing suspicious was found on the plane that landed at Burlington International Airport.

United Airlines flight 3613 was grounded Sunday at Burlington International Airport in Vermont after a bomb threat was found on a note left in a lavatory. The 65-passenger, 4:30 pm flight from Newark, New Jersey, was held for hours while officials searched for any sign the threat was real.

NBC reports that in a press conference, airport director of aviation Nic Longo said that roughly 20 minutes prior to its landing, the flight crew told Burlington's control tower there was "a threat to the aircraft." Longo did not offer specifics about the threat, but an NBC affiliate acquired a recording of the pilot of 3613 saying that a "flight attendant just came up and said that a passenger found a note ... that said there was a bomb on board."

Per emergency response protocols, the plane was sent to a special location to allow an assessment of the situation by the Vermont State Police bomb squad and additional local and federal authorities.

Passengers described K-9 units sweeping the plane, with one describing the experience as "scary." Another, Phil Baruth, said that it was "unfair" that the threat "ruined everyone's days."

"Obviously someone a little deranged," Baruth said. "On the other hand, authorities here handled everything perfectly and at no time did I feel unsafe."

This is just the most recent threat of its kind to disrupt flights since late February. A threat on February 17 diverted an American Airlines flight in Texas and a Spirit Airlines flight was evacuated at a New Hampshire airport for a bomb threat on February 11.

In Burlington, according to NBC, investigators could not find a credible threat, and there were no arrests. The FBI is leading an ongoing investigation of the incident.