Fire officials now believe the Madre fire above Azusa can be contained by Friday morning, thanks to favorable weather conditions and an aggressive aerial assault.
The fire, which started Monday evening in San Gabriel Canyon north of Highway 39, is now 70% contained, according to the U.S. Forest Service. It is estimated to have burned 250 acres so far.
The aggressive air assault appeared crucial because the area is a maze of steep terrain sometimes difficult for crews to access on foot.
"Aircraft are making good progress," Forest Service spokesman John Miller told The Times earlier Tuesday.
The number of people battling the blaze tripled from 150 on Monday to 450 on Tuesday.