A fire that has blackened about 1,800 open acres on Camp Pendleton was 80 percent contained Friday, authorities said.
It's not known why the so-called Horno Fire broke out about 1 p.m. Thursday near the intersection of Horno Canyon and Basilone roads, Camp Pendleton spokesman Sgt. Christopher Duncan said.
The fast-moving blaze had charred about 600 acres by about 2:30 p.m. Thursday, according to CalFire, which was assisting Camp Pendleton firefighters.
No structures were threatened, authorities said.
According to the most recent update the blaze's growth had slowed significantly as of 5:45 p.m.
