Airline passengers detained

Airport security was on high alert Sunday after suspicious activity led to three arrests. / The Consumerist (Flickr)

Frontier Airlines says three passengers were detained at Detroit's Metro Airport after the crew of a flight from Denver reported suspicious activity.

The Transportation Security Administration said in a statement that the report Sunday afternoon prompted NORAD officials to send F-16 jets to shadow the flight until it landed safely in Detroit- a step the agency said was taken "out of an abundance of caution."

Frontier spokesman Peter Kowalchuck said Flight 623 landed without incident in Detroit Sunday. Police took three passengers into custody after the crew reported two people were spending a long time inside a bathroom plane during the flight.

Detroit Metropolitan Airport spokesman Scott Winter says the Frontier flight crew radioed to request police help when the plane landed, prompting responders to greet the flight and question passengers after the aircraft taxied to a remote location at the airport.