Am I liable to pay for damage on other drivers car?

My 14 year old son and his friends stole my 19 year old sons car that he left home when he went in the military. The car is in my name. He totalled the car during a joyride and involved in a hit and run accident while I was having surgery. Am I liable for damages to the other drivers car? I have received a letter from the other drivers insurance company addressed to me as if I was involved in the accident attempting to collect money for the other drivers damage.