TOWNSEND -- The Bear Gulch fire, burning about 12 miles east of Townsend, grew another 150 acres to 750 acres Tuesday afternoon.

"The fire made significant runs," Incident Commander David Nunn said Tuesday afternoon, while eyeing the large plume of smoke.

Three 20-person crews finished a hand line on the west side of the blaze and are now working on the eastern flank. Nunn said the fire was 10-percent contained as of Tuesday evening.

The four helicopters and two air tankers attacking the flames were grounded Tuesday afternoon because of the 35 mph wind gusts fanning the fire, which is burning in heavy timber, Nunn said.

A Type 2 incident management team arrived on the scene Tuesday afternoon and is expected to take over the fire this morning, according to fire information officer Virginia Knerr.

Bear Gulch is the first sizable fire in the Helena National Forest this year, Nunn noted.

For safety reasons, authorities closed North Fork of Deep Creek Road and Cabin Gulch Road.

Crews are providing structure protection on five nearby houses -- two primary residences and three seasonal -- about 100 feet from the heel of the fire. The houses are "threatened but not in immediate danger," Nunn said. There are no structures to the front of the fire, he added.

The cause of the fire, which was reported at about 2 p.m. Monday, remains under investigation.

Another round of thunderstorms and gusty winds today may spell trouble for firefighters but those also bring cooler temperatures.

"Hopefully we can corral it and get a hold of it," Nunn said.

Nunn said there has been exemplary cooperation between the involved agencies, which includes the state Department of Natural Resources and Conservation, Townsend Ranger District, Helena National Forest, Broadwater Rural Fire Department, Broadwater County Sheriff's Office and the Bureau of Indian Affairs.

Reporter Angela Brandt: 447-4078 or angela.brandt@helenair.com