CORONA, Calif. (AP) — Firefighters working in steep canyons Tuesday got help from retardant-dropping aircraft flying around-the-clock as they saved homes from a smoky blaze that surged through suburban canyons in Southern California and sent hundreds scrambling for safety.

One structure burned, but shifting winds eventually sent flames away from neighborhoods in Corona, Anaheim and Chino Hills. At least 500 homes remained under mandatory evacuation orders but authorities were hopeful some residents would be allowed to return later in the day. That could depend on the behavior of gusty, dry winds moving through the region amid an autumn heat wave.

The fire sent up a huge plume of smoke and rained down ash as it swiftly grew to more than 3 square miles (7.7 sq. kilometers) after starting at 1 p.m. Monday in canyons about 50 miles (80 kilometers) southeast of Los Angeles. It was just 5 percent contained late in the evening.

Smoke drifted some 40 miles (64 kilometers) east to the ocean and authorities warned of potentially dangerous air quality.

Fast-moving firefighters were able to beat back the blaze, keeping damage to a minimum as over 1,000 people evacuated at the fire’s height.

Jeff Peterson of Corona arrived at his home of 17 years about two hours after the fire had been burning. The wind appeared to be blowing the fire away from his house as he watched it with a neighbor.

Then the wind changed, and so did his mood.

“We just looked at each other and said, ‘it’s time to go get the valuables,'” Peterson told the Orange County Register.

Flames crept down hillsides to the shoulder of State Route 91. The freeway acted as a fire line blocking the fire’s spread.

But with some lanes closed, traffic was backed up for several miles. The Tuesday morning commute was likely to be difficult.