A fast-moving brush fire dubbed the Archer Fire broke out Sunday evening in the Whittier Narrows Natural Area near El Monte, California, prompting an aerial assault and precautionary evacuations. Initial reports placed the blaze at roughly one acre, burning in medium-to-heavy vegetation under a southwest wind. Within minutes the fire ballooned to about 10 acres, and incident commanders warned it could ultimately scorch more than 50 acres if winds persisted. The Los Angeles County Fire Department dispatched ground crews and two water-dropping helicopters from its Air Operations unit to slow the westward advance. Firefighters ordered food vendors operating along nearby Rosemead Boulevard to leave the area while containment lines were secured. No structures were immediately threatened and no injuries had been reported as of late Sunday. Investigators have not yet determined what sparked the blaze.