A fire fueled by brush and grass scorched more than 7,000 acres just outside of Los Angeles, forcing several hundred people to flee and threatening homes in the foothills of the San Gabriel mountains.

Winds as strong as 50 mph are feeding the blaze, making it more difficult for firefighters to contain it, Los Angeles Fire Department spokesman Jim Wells said in a telephone interview. The fire started yesterday afternoon near the intersection of the westbound 118 freeway and Topanga Canyon Boulevard in Chatsworth, about 30 miles from downtown Los Angeles, Wells said.

``The winds are the most important factor here, because they will either allow firefighters to get the upper hand on it or cause the fire to continue to spread,'' Wells said.

More than 1,300 firefighters are battling the blaze, which was about 5 percent to 10 percent contained as of about 8:45 a.m. local time, Wells said. At least five structures have been destroyed, including a home, a detached garage and three outbuildings, said Chris Freeman, a spokesman for the Los Angeles County Fire Department.

The fire has destroyed at least one building at Boeing Co.'s Santa Susana Field Laboratory in Ventura County. The facility was part of the company's Rocketdyne division until its sale in August to United Technologies Corp., spokeswoman Inger Hodgson said in a telephone interview.

The blaze is moving southwest, said John Mancha, an inspector with the Los Angeles County Fire Department. Temperatures in the region have been in the high 80s and low 90s, he said.

``It's very dry, it's warm, you have low humidity,'' Mancha said in a telephone interview. ``Just the winds yesterday definitely drove this fire. We have a lot of work ahead of us.''

One city firefighter was injured when he was hit in the back by a 40-pound boulder and knocked unconscious for about five minutes, Wells said. The victim was taken to Providence Holy Cross Medical Center, where he was treated and released, Wells said.

PHOTO CAPTION

A horse runs free in the burned out fire area on Woolsey Cyn Rd in the West Hills area of Los Angeles September 29, 2005. (REUTERS)