Cooler, wet weather helped firefighters make progress on a huge Northern California wildfire that destroyed nearly three-dozen structures, forced the evacuation of more than 2,000 people and forced the cancellation of a sporting event because of the smoke.

More than 5,000 firefighters — from as far as Florida and Alaska — managed to increase containment of the fire from 10 to 17 percent on Sunday, said Capt. Tom Piranio, a state fire spokesman. The number of acres burned held steady at 128 square miles.

"The heavy drizzle helped the firefighters immensely. We got what we were looking for to gain containment of the fire," he said.

But earlier in the day, poor air quality forced a last-minute cancellation of two popular Ironman events in nearby Lake Tahoe, disappointing about 3,000 athletes who had signed up for the competition, Ironman operations manager Keats McGonigal said.

"County air quality officials have recommended that the event be cancelled," said a statement announced to participants.

"I had tears too, and then my husband came, and comforted me," Sabine Bokslopper told KTVU, as she unpacked her gear bags in Oakland Sunday evening.

Bokslopper was one of eight members of the Tri-Valley Triathlon Club, trained and ready for the 140 mile endurance race: swimming, cycling, and running. "I was hoping to finish in 16 hours," she added.

The wildfire about 60 miles east of Sacramento started Sept. 13, threatening more 21,000 structures. According to preliminary figures released Sunday, the fire destroyed 10 homes and 22 outbuildings in the White Meadows area of Pollock Pines.

Piranio said assessment teams were headed back in the rugged, steep terrain to survey more damage.

"It has been very challenging to get access to those burn areas because there's a lot of inaccessible terrain," he said. "We had to make sure it was safe enough to enter."

About 100 evacuees have been allowed to return home, but some 2,700 remain under evacuation orders, state fire spokesman Daniel Berlant said. The fire also continues to threaten a key University of California, Berkeley research station that is home to scores of experiments on trees, plants and other wildlife.

A man charged with starting the fire, Wayne Allen Huntsman, 37, pleaded not guilty to arson Friday and remains in the El Dorado County jail on $10 million bail.