More than 600 firefighters from Alabama, Arizona, New Mexico and Utah were holding back flames on a fire that exploded along the Green River and burned more than 1,500 acres of prime river front.

Hot dry winds and low humidity fanned the blaze from 250 acres Sunday to 1,500 by Monday afternoon. Crews Tuesday morning declared the fire 60 percent contained, but no there was no estimate for complete containment."This fire will be in the millions of dollars in damage" when crews finally extinguish the flames, said Mike Stubbs, fire information officer for the Ashley National Forest.

Meanwhile, firefighters and Utah State Prison crews contained the Aperson Creek Fire in Echo Canyon, which burned more than 550 acres. But two fires in Utah's West Desert, both started by lightning Monday, continued to burn throughout the night.

However, fire officials expected to have the Marble and East Grassy fires contained Tuesday.

In Flaming Gorge National Recreational Area, investigators have traced the cause of the blaze to fireworks, Stubbs said.

"Some citations have been written," Stubbs said, adding no arrests were made as of Tuesday morning. "Basically it appears that there were two individuals with fireworks of some sort down at the spillway boat ramp and were lighting them, and one went across the river."

Fireworks of any kind are illegal on federal lands, Stubbs said. The maximum penalty for fireworks possession is $500 and/or a six-month jail term.

"But the citation for starting a fire on a national forest is a felony, and they could be liable for all suppression costs and restitution to the power company," which is paying for planes to drop retardant on the fire, Stubbs said. "Our hope is these people do get cited and hopefully they can serve as deterrents."

A force of 180 firefighters was building a firebreak along the south side of the blaze while crews to the north were using eight pumper trucks to hose down flames. Ten hand crews of 20 people each, six bulldozers and three helicopter, five tankers and a guide plane were also fighting the fire burning on the southeast side of the Green River.

The blaze, just below the Flaming Gorge Dam on the Utah-Wyoming state line and about 20 miles west of the Utah-Colorado state line, began about 3 a.m. Saturday in dry timber and brush.

"The value of the land is not terribly high," Stubbs said. "But the Green River below the dam is one of the top fisheries in the nation," and sediments caused by land stripped of vegetation severely damages fishing.

The main fear of fire bosses was if winds push the flames uphill into areas containing large amounts of dead timber and dry fuels, he said.

The weather may cooperate, Stubbs said, with temperatures dropping and humidity increasing. Winds are another story.

No river runners or campers are in danger of getting in the fire's path, Stubbs said. Forest visitors, however, were asked to watch for fire traffic, park only in designated areas and observe speed limits.