DENVER » An unspecified security threat that led authorities to check a Southwest Airlines plane after it landed at Denver International Airport has been determined to be not credible, the FBI said.

Amy Sanders, a spokeswoman for the FBI, told the Denver Post in an email, "The threat was deemed non-credible at this time," but she would not identify the nature of the threat.

No one has been detained or arrested "at this time," Sanders said.

The Post reports that authorities were made aware of the threat about 5:15 p.m. and the plane landed safely at the airport at 6:36 p.m.

The 126 passengers were shuttled to the main terminal by bus, airport spokesman Heath Montgomery told the Denver Post. Montgomery identified the plane as Southwest Flight 3456.

Southwest spokesman Brad Hawkins said he could not detail the nature of the threat.

"Out of an abundance of caution, the captain in command of Flight 3456 from Baltimore/Washington to Denver has stopped short of the gate after an uneventful landing to allow the authorities at Denver International Airport access to the aircraft," Hawkins said in an email to the Post.

"We don’t have further details to share except to reiterate that the safe operation of every flight is a shared priority of all agencies and operators involved in commercial aviation. Our employees are working with any of the 126 customers whose travel plans will be impacted by the delayed arrival at the terminal."