A forest fire northwest of Lillooet, B.C., has grown to 800 hectares, according to forestry officials. (CBC)

More forest fire crews are being sent to battle a blaze that has grown to 800 hectares in southwestern B.C.'s Bridge River valley, as residents prepare for more evacuation orders.

B.C. Forest Service fire information officer Elise Riedlinger said that the fire northwest of Lillooet was only 10 to 15 per cent contained on Tuesday morning.

"Obviously we're concerned about the hot temperatures this afternoon and the heavy wind and our top priority remains protecting the property in the immediate area. So crews are going to be focusing on that southwest flank near the structures," said Riedlinger.

No buildings have been lost in the fire, but residents of least 25 properties between Tyaughton Lake and Gun Lake have been ordered out, and hundreds more in the area are on evacuation alert, in case the order is expanded.

The fire has been fueled by hot dry winds sweeping down from the Coast Range Mountains, as much of B.C. is locked in an unusual heat wave.

About 60 firefighters were already fighting the fire, and another 40 were en route on Tuesday. Six helicopters and one airtanker were also deployed at the fire.

Casie Menhinick, the co-owner of Spruce Lake Wilderness Adventures in Gold Bridge, told CBC News she and her five children left their home for safer ground on Monday, but the hardest part of the ordeal has been the lack of information she's getting from the B.C. forest service.

"We would like to see more communication, more media postings," she told CBC News on Tuesday morning. "Not once every 12 hours, but even every couple of hours, because it's a roller-coaster. I get a phone call that everything is OK and three hours later the fire is raging right pretty well on your property."

About 67 customers are without power south of Tyaughton Lake Road because of transmission circuit failure. Highway 40 between Gold Bridge and Lillooet remains closed because of the fire.