Auto Insurance Claims: cleanup cost due to trailer of hay fire on hwy, auto insurance company, cal trans

Question
A friend called me and said she has recieved a bill from Cal Trans for $3200.She was driving her covered vehicle towing an unowned trailer of hay she purchased.The hay caught fire and burned most of the hay and some of the trailer.Cal trans came out to clean up the remaining Hay left on the shoulder of the Highway. Which part of the auto policy would provide coverage for the cost of the cleanup and if not the auto policy- would she have coverage from her Homeowners?  She also asked me if I thought this claim would raise her insurance.

Answer
Hi William,
Your friend needs to report this incident to her auto insurance company (the only possible source of coverage).
If, after investigating, they determine that the policy will cover this loss, it will be paid under the property damage portion of her policy.
There is no possibility that the homeowners policy could provide coverage.
I hope this information has been of help.
Your feedback by rating my answer will be appreciated.
Sincerely,
Bennie
San Francisco Bay Area