Authorities say a wildfire north of Los Angeles has destroyed at least three homes and is threatening thousands more.

Captain Mike Dietrich -- the incident commander for the U.S. Forest Service -- said at a news conference Saturday night that the fire was "the perfect storm of fuels, weather and topography coming together" and called the situation "very treacherous."

He says firefighters have discovered three burned homes in remote sections of the Angeles National Forest and are looking for more that may have been destroyed.

The fire near the mountain communities of La Canada Flintridge and Altadena had tripled in size Saturday to more than 31 square miles, sent huge billows of smoke over Los Angeles and left three people injured.