Direct cause - Unknown. What I do know however was that the automatic emergency break system on my vehicle was activated, causing the vehicle to stop in the middle of driving. This resulted in the vehicle behind me hitting my car. Prior to the incident occurring, no warning indicators (lamps, messages, etc.) came from the dashboard. The vehicle just stopped. Immediately after this accident occurred. I turned off the forward collision safety feature, as I was scared of the issue (vehicle stopping) repeating itself. To date, my vehicle has not been repaired or my insurance agency contacted, as I do not believe I should be held responsible for the cost of this repair.