HIGHGROVE, Calif. -

A brush fire broke out today near Highgrove, scorching around 10 acres of open land as fire crews attempted to get a line around it.

The wildfire was reported around 1:45 p.m. along Pigeon Pass Road, near Highgrove Pass Road, roughly a mile south of the Riverside-San Bernardino County line.

Riverside County fire crews, with the support of city of Riverside and Cal Fire personnel, were working to contain the blaze.

Eighteen engine crews and a dozen inmate hand crews -- numbering close to 250 firefighters -- were contending with steep, rugged terrain, leaving it to six air tankers and four water-dropping helicopters to take care of most of the initial fire attack operations.

A fire battalion chief at the scene reported flames were moving slowly. However, he said crews were deploying for structure protection on the north side of the wildfire.

There was no immediate word on how it started.