SEATTLE — Alaska Airlines had to delay a flight about to leave Seattle-Tacoma International Airport when a rat was seen scurrying in the cabin.

The airline says the flight from Seattle to Denver had just pulled away from the gate Thursday morning when the little stowaway was spotted. The 737 jetliner returned to the terminal and passengers and crew boarded another plane about 90 minutes later.

Airline spokeswoman Bobbie Egan says the plane won't be returned to service until maintenance workers make sure the rat didn't damage equipment or chew any wires _ and an exterminator certifies the plane is rodent-free.

Egan says workers also are trying to figure out how the rat got aboard. She says in cold weather, "sometimes rodents can seek shelter in strange places."

Airline officials tried to downplay the rat on board by claiming the rat in question was only a tiny field mouse, not much larger than a Madagascar hissing cockroach. But when the rat was finally cornered and stomped to death by an exterminator it proved to be much larger than it had been portrayed, measuring about 7" not counting its tail. A self-taught expert on rats said a rat that large was capable of devouring an infant, which would have triggered a very large lawsuit had the rat actually eaten an infant, if there had been an infant on board, which there was not.