A 2-acre brush fire was threatening homes in the San Gabriel Valley suburb of Walnut, just west of Diamond Bar, officials said.
"It is very close to homes at this point," said Los Angeles County fire inspector Quvondo Johnson. "It started in the brush, but it's close to homes."
The brush fire broke out at 3:50 p.m. and officials called a second alarm at 4:07 p.m.
The fire ignited near the 600 block of North Silver Valley Trail.