A catalytic converter cannot start a fire when the vehicle is on the side of the road or driving by, these fires were in ditches with trees and brush and not accessible by a vehicle.. I was at the Bogard fires before Responders arrived and took pictures. I believe someone intentionally drilled holes up by the exhaust manifold and pulled the catalytic converter out, then u build up speed turn the key off, and keep your foot on the throttle and turn the key back on and it'll explode meaning it'll backfire and throw carbon sparks and fire. 
I personally think this was intentional.