3 Firefighters Are Burned in Blaze Flare-Up : Brush fire: Three others suffer smoke inhalation as firefighters hold 3-day-old Rainbow blaze to firebreak perimeter.

Three firefighters were burned and three others were treated for smoke inhalation Tuesday when a backfire they had set to help control the three-day-old Rainbow fire flared up over them, authorities said.

The most seriously injured was a California Department of Forestry captain from Ventura County, who suffered second-degree burns on his hands, neck and arms and was airlifted to San Bernardino County Medical Center’s burn center, said CDF spokeswoman Beverly Atkins.

Two state inmates working in the Ventura crew received minor burns, and three other firefighters--two other inmates and a volunteer Temecula firefighter--suffered smoke inhalation, Atkins said.

Despite the injuries, the backfiring strategy worked well in keeping the blaze within the six miles of perimeter firebreaks cut by bulldozers, Atkins said, and containment of the fire was expected by nightfall Tuesday.

The increase in the amount of acres consumed by the fire, from 1,650 acres on Monday to 3,000 acres late Tuesday, reflected previously unburned vegetation within the fire lines that was set afire with the backfires on Tuesday, Atkins said.

Unlike on Monday, when the fire broke momentarily through the firebreaks and destroyed a wood-frame home near Pala-Mesa Road in Riverside County, there were no surprises on Tuesday, Atkins said.

CDF investigators say the fire was started intentionally about 3 p.m. Sunday, but no suspects have been identified.

No other structures have burned, and CDF officials say they saved 45 homes that are located along the hillsides and in the canyons of the rural area straddling the Riverside-San Diego County line just east of Interstate 15.