Since this was a rear-end collision, there isn't any realistic response you can provide to claim that you were not at fault.Injuries don't always manifest themselves at the time of the accident, and injuries may appear later even in low speed collisions.The specific injuries may not be known until the parties complete their medical treatment (which could take a number of months) and then seek compensation from your insurance company for their medical bills, pain and suffering ( an amount in addition to the medical bills) based on the medical reports.It would be advisable to let your insurance company handle the entire matter.  Most likely, the case will be settled with your insurance company without a lawsuit being filed.  If the other parties are dissatisfied with settlement offers from your insurance company after they complete their medical treatment, they could reject the settlement offers and file a lawsuit for negligence against you.  Don't worry about it because it might be two years before a lawsuit is filed and again, no lawsuit is filed if the case is settled with your insurance company.  In the event of a lawsuit, your insurance company will provide you with an attorney at no cost to you and that attorney will handle the entire matter for you.  Again, I want to emphasize, don't worry about it.  Your insurance company will handle the entire matter and most likely the case will be settled without any lawsuit being filed.