DENVER -- Four storage tanks holding more than 2 million gallons of jet fuel caught fire yesterday near Stapleton International Airport, snarling comings and goings at the terminal as holiday travelers headed home after Thanksgiving.

A fire at a holding pond that had collected some of the spilled fuel was extinguished with foam, but authorities feared it might reignite and spread to a nearby 2 million-gallon fuel tank.

Firefighters had been trying to cool two 800,000-gallon tanks containing jet fuel throughout the day, spraying them with strong jets of water, but they caught fire about 10 p.m.

When the two tanks ruptured, firefighters had to be pulled back. The tanks were designed to rupture, rather than explode, when overheated, officials said.

An attempt to snuff that part of the fire with foam failed.

"We didn't have the capacity to provide foam in the amount needed," Fire Chief Rich Gonzales said.

Three firefighters were treated at Denver General Hospital for dehydration and heat exhaustion and two others were treated for smoke inhalation at the scene, but the fire caused no serious injuries.

Smoke from the blaze cast a pall over metropolitan Denver and caused visibility problems on nearby Interstate 70, which remained open.

Norm Avery, a Stapleton spokesman, said the airport was open, but United Airlines was forced to delay, cancel and divert flights because of a fuel shortage.