SEATAC, Wash. -- Flight 980, an Airbus 320 with 142 passengers and 5 crew members on board, left Seattle at about 12:33 p.m. and was turned around as a precaution, authorities said. It landed at Sea-Tac at about 1:15 p.m.

RAW VIDEO: NWA Flight Returns To Sea-Tac
VIDEO: Bomb Threat Causes Airport Chaos
Statement By Northwest Airlines

Video from Chopper 7 showed the plane held on a tarmac on the airport's west side for about an hour before it moved to a location where passengers and bags were unloaded.

Chopper 7 video showed bomb-sniffing dogs searching bags as passengers were loaded onto buses around 3 p.m.

Airport police took into custody a man who told a gate agent there was a bomb on the plane shortly after it departed, airport spokeswoman Terri-Ann Betancourt told the Associated Press.

She said police did not believe the bomb claim was a credible threat.

The man was never on the plane, and initially said he had no luggage on the aircraft, Betancourt said.

He later told authorities he had checked luggage under someone else's name.

Betancourt said she would not release any information about the man being questioned unless he was booked into jail.

In a statement, Northwest Airlines said "the passenger's statement has been deemed not credible and the passenger in question has been taken into custody."

A Northwest spokesman said the airline "apologizes to its customers for the inconvenience and expects flight 980 to depart Seattle as soon as possible."

Sea-Tac's center runway -- the western of the two runways currently in service -- was closed during the incident, Chopper 7 pilot Clark Stahl said. The closure caused a 12-plane backup of flights waiting to depart at one point.