A fast-moving wildfire dubbed the Bert Fire erupted shortly after 2 p.m. Tuesday near The Old Road and Biscailuz Drive in Castaic, north of Los Angeles. Driven by dry brush and triple-digit heat, the flames quickly expanded from an initial estimate of four acres to 46.7 acres, according to mapping by the county’s Intel 24 reconnaissance aircraft. Los Angeles County firefighters deployed ground crews, two water-dropping helicopters, Helitanker 55 and additional aircraft to slow the advance, while deputies ordered evacuations for nearby neighborhoods as the blaze threatened homes and high-tension power lines. The department said forward progress was halted at 4:05 p.m., and by early evening crews had fully lined the roughly 47-acre perimeter. No structures were damaged and no injuries were reported. The cause is under investigation. The incident comes amid Southern California’s first significant heat wave of the season, which has elevated fire danger across the region. In neighboring Riverside County, firefighters continued to work on a separate blaze in Jurupa Valley that scorched about 150 acres and was 50% contained as of Tuesday morning.