Nick Quintana, a spokesman for the Cumbres and Toltec Scenic Railroad, spent most of Wednesday night at the site of a fire that severely damaged the steel and wood Lobato Trestle, the second-highest bridge on the 64-mile route between Chama, N.M., and Antonito, Colo.

Quintana said that when he arrived at the trestle, which is about four miles north of Chama, three-quarters of the bridge — if not 80 percent— was burned.

"My heart was in my throat," he said. "It's my favorite trestle, even though Cascade is higher. But this one, it's got quite a bit of class to it."

The blaze, which burned railroad ties and bent the track on the 310-foot span, sent debris plunging into the ravine 100 feet below.

Operations out of the Chama Depot have been suspended for an undetermined period of time. Passengers may ride a bus to Antonito and board the steam-powered, narrow-gauge railroad train there for Osier, with a return to Antonito.

The cause of the fire has not been determined.

On Thursday, hand crews from the New Mexico State Forestry Division and the Bureau of Land Management were creating a perimeter around the approximately 2-acre burn area.

"The fire on the ground is minimally active. There's a lot of smoldering," said spokesman Dan Ware. Helicopters will be dropping water to cool off what he described as a "valuable riparian area."

Firefighters also worried that the railroad ties still burning on the trestle might continue to fall into the ravine. "Those ties will burn for a little while," Quintana pointed out, because they contain creosote.

Ware said railroad crews tried removing some of the ties from the path of the fire but they "got close and had to pull off."

Two New Mexico state fire marshal's office investigators were on the scene Thursday looking into what might have sparked the fire — everything from stray embers to arson — although lightning has been ruled out. New Mexico State Police are also conducting an inquiry.

Tuck Miller, owner of a Chama bookstore and coffee shop, said he walked downstream from the trestle, which crosses the East Fork of the Wolf Creek, on Thursday. "It's very dry and the fire danger is extremely high," he said.

A number of people in the town of Chama reported hearing some sort of explosion about an hour before the fire was reported. But the sound might not have come from the bridge, Ware said, and might simply have been fireworks being set off.

Local volunteer fire departments were the first to respond. The trestle is less than four miles from Chama. The bridge itself is more than 100 years old although new ties were laid about 15 years ago.

In a news release, Marvin Casias, general manger for the railroad, called this "the most significant mishap to the track and right-of-way in all the 40 years the Cumbres and Toltec has been in operation."

The fire happened just as the tourist season was getting started and as the tourist train celebrates its 40th anniversary. It is in the midst of a multi-year program to replace ties and ballast. A total of 40,378 new ties have been installed so far.

The Cinder Bear Express, a children's train with storytelling, singing and a picnic lunch that is offered out of Antonito on Thursdays during the summer, ran on schedule Thursday.

But, Quintana admitted, "It's been a rough day. I don't know what we're up against."

Contact Anne Constable at 986-3022 or aconstable@sfnewmexican.com.