( CNN ) -- The FBI questioned passengers from a Delta Airlines flight from Detroit to Denver on Friday after a potential security threat . `` The majority of the Delta Flight 1500 passengers have been allowed to claim their luggage and continue with their travel plans , '' FBI spokesman Dave S. Joly said . The screening that included police officers with the K9 unit delayed their arrival at the terminal by about four hours . `` Why did it take so long ? What was the real holdup here ? What were they really looking for ? '' asked Jace Booher , according to CNN affiliate KDVR . A law enforcement official told CNN that a bomb threat found written on a note prompted the security screening after the plane landed at Denver International Airport . The 737 aircraft , which was carrying 151 passengers and six crew members , landed safely at 4:40 p.m. MT as scheduled , said Russell Cason , a spokesman for Delta . The plane was taken to a remote location at the airport for the screening . Teen arrested for tweeting airline terror threat . Sources : Airlines warned to beware of possible shoe bombs . CNN 's Pamela Brown and Matthew Stucker contributed to this report .
Official : The threat is found on a note . Flight lands safely at Denver International Airport . The FBI interviews passengers at a remote airport location .