Some states have what is referred to as comparative negligence. Comparative negligence comes into play when it is contended that two or more parties failed to perform at the standard of the "ordinary reasonable person". For example, suppose one person was driving too fast in a patch of dense fog on the highway and hit a car -- but the car that was hit did not have its lights on as it should have.
You should report this loss to your insurance company as well as the other party's insurance company. The claims adjuster from each will work with you to determine who is responsible for what. If all parties cooperate then your claim should be handled rather quickly.
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