Riverside County firefighters are taking on a fast-moving 50-acre blaze in Rancho Jurupa Regional Park that is burning near a number of homes and buildings.
Fire spokeswoman Jody Hageman says power lines are down in the area at the south end of the park, where the fire was reported at about 4:45 p.m. Thursday.
The fire went from 10 acres to 50 in about an hour.
More than 140 firefighters, a helicopter and other equipment have been dispatched to the fire that is sending up huge billows of smoke that are visible throughout the region.
The National Weather Service issued a wind advisory for gusty offshore winds in Riverside County valleys, which may be fanning the flames. The advisory is in effect until 2 p.m. Saturday.