CARLSBAD, Calif. — Flames engulfed suburban homes and shot up along canyon ridges in one of the worst of several blazes that broke out Wednesday in Southern California during a second day of a sweltering heat wave, taxing fire crews who fear the scattered fires mark only the beginning of a long wildfire season.

Thick black smoke darkened blue skies over the Pacific coast city of Carlsbad, about 30 miles north of San Diego, known for its Legoland California amusement park. The park was closed Wednesday because of a power outage caused by the fire.

At least two firefighters suffered minor injuries — one heat-related and one from smoke inhalation — since Tuesday.

Thousands were asked to evacuate their homes in Carlsbad after the blaze erupted at about 10:34 a.m. Wednesday and spread through rapidly heavy brush before jumping into residential areas.

Despite a state fire report of 30 homes burned earlier in the day, Carlsbad Fire Chief Michael Davis said he knows of just three homes destroyed and about a dozen damaged, all of them in the same neighborhood.