"Hey there, so sorry, I was in a minor car accident and was unable to notify you. Everyone is fine, and I'm really sorry for this unfortunate circumstance. I'd be happy to find a time soon to reschedule if possible, thanks you for your understanding."

Jobs lie to us all the time, lie back, fuck 'em. Come up with any excuse you need to in order for them to reschedule. Shit happens, I've rescheduled interviews before, it's not that big of a deal.