Authorities say firefighters backed by water-dumping helicopters and planes are gaining ground on a wildfire in the Angeles National Forest that has forced the evacuation of about 1,200 people.

Los Angeles County Fire Department spokesman Ron Haralson says the blaze has charred up to 750 acres in the rugged area of Little Tujunga Canyon, about 20 miles north of downtown.

Haralson says firefighters are "getting a really good handle" on the blaze started about 2 a.m. Sunday, but he warned that Santa Ana winds are expected to kick up in the evening. The gusts could spread embers.

No structures were damaged. One firefighter and one resident reported minor breathing problems.

The cause of the fire is under investigation.