I cant find anything about the conclusion as to the cause of the previous fire using azuza San Garbriel....or any other related terms ...
The latest on the local news is that the fire has grown to 40 Acres , but that the winds have died down.
This is good because I think the water dropping helicopters and planes can't fly at night.
They also mentioned that the cause of the fire is still under investigation.
http://ktla.com/2013/09/23/brush-fire-burning-in-mountain-above-azusa/#axzz2fmlUFBgd