As if the scarred flesh over a third of his body weren't enough, Mark Keller got a tattoo to mark the day he and two other volunteer firefighters were burned while battling a grass fire in central North Dakota.

"It's just a reminder to myself that I made it out alive," said Keller, who is marking the third anniversary of the blaze that also injured firefighters Geremy Olson and James Meyer near Wilton, north of Bismarck.

This year's fire season already is in full swing. The National Interagency Fire Center in Boise, Idaho, says more than 12,000 wildfires have burned more than 1 million acres so far. About 100 similar blazes have been reported in North Dakota.

Last year, wildfires scorched 9.3 million acres nationwide, the agency said.

Agency spokeswoman Jennifer Smith says 111 firefighters have died battling wildfires between 2003 and 2006, the most recent numbers available. The group does not keep injury statistics.

Those who survived the blazes, like Keller, Olson and Meyer, use their scars to teach others.

Keller's tattoo above his right ankle depicts a fire department logo capped with flames, along with his name and those of his burned buddies. The tattoo, like his surgeries, is unfinished.

"I'll add smoke to it later," said Keller, 36, who also is a Burleigh County deputy.

The 2005 grass fire that injured Keller blackened a 6-mile-long swath near Wilton. It was traced to a pile of trees that had been smoldering undetected for nearly a month.

Meyer had been hired to burn the tree piles on his neighbor's farm. He said he torched the dozen or so massive tree piles when the ground was covered with snow in March. When the ground dried out a month later, embers from the still-burning woodpile ignited grass, and the fire spread, he said.

The firefighters were hurt after the wind-driven fire engulfed them and the heat from the blaze sucked oxygen out of the air, killing the engine in the fire truck in which they were riding.

"I tried starting it three or four times and it wouldn't kick over," Keller recalled. "From there, it just got hotter and hotter and hotter. My brain told me to flee."

Fire officials estimated that heat from the blaze topped 2,000 degrees - near the melting point of steel.

Keller was on fire when other firefighters rescued him, dousing him with water. He was the only one of the three who was not wearing full bunker gear - and he was the most seriously injured, suffering second- and third-degree burns to about 30 percent of his body.

Keller spent two months at a Minneapolis-area hospital recovering, and has since returned 17 times for more surgeries. In May, he's slated to have another surgery to remove his trachea, which was damaged by a device put in his neck to aid his breathing.

Meyer, 28, who suffered second- and third-degree burns on his face, was released from a Bismarck hospital a few days after the fire. Olson, 33, had third-degree burns on his right foot and left arm, and broke his left leg while running from the blaze.

Olson is now a volunteer firefighter in Washburn; Keller and Meyer are still volunteer firefighters in Wilton, though Keller's injuries have forced him to concentrate on dispatching and training instead of battling fires.

Wilton Fire Chief J.D. YoungBird said the department has not changed its procedures after the fire but the more than 40 firefighters in the crew are more cautious, and always wear their bunker gear.

"I think it has been pretty tough on them, but we're glad to have them back because they have a lot of experience," YoungBird said.

Keller has been assigned mostly to desk duty at the sheriff's department since the fire. He hopes to return to his patrol car soon - "just to show that I can do the job," he said. "I enjoy being a deputy."

Olson now works for the state Forest Service as a fire planning and prevention specialist. He spent the third anniversary of the Wilton fire helping monitor a controlled burn near the Garrison Dam.

"My goal is for 2008 to be the first year that I will not have to have surgery," said Olson, who has had surgery about 10 times since he was injured.

"I go all over the state free of charge, talking about the lessons I've learned," he said. "A bad thing happened to me and I want to make sure it doesn't happen to somebody else."

North Dakota averages about 500 grass fires a year, and about 90 percent are sparked by humans, he said.

"I encourage people to think before they burn, and make some good, wise decisions," Olson said.

Keller sued D.J. Coleman Inc. and Clark Coleman, who hired Meyer to burn trees on the property.

Keller and Scott Porsborg, attorney for the defendants, said an out-of-court settlement was reached but they could not discuss details.

Olson, who was a self-employed television producer before the blaze, said he was unable to work for 13 months, and was helped by donations from other North Dakotans.

"What the state gave us wasn't enough," Olson said. "If it wasn't from the support of community, we wouldn't have made it."

Meyer, who farms near Baldwin, said he believes the fire three years ago spurred county officials to ban burning more quickly in dry conditions.

The three firefighters remain friends, and Olson, at least, has never lost his sense of humor.

"With all the money we've spent on plastic surgeons, we still look as bad as we did before the fire," he said.