what is problem with cybex treadmill?

at gym and stepped onto what looked like a stationary treadmill. Before reaching front of treadmill it went off at 7k. I didn't get near any buttons to set up programme and 2 people witnessed the fact that the treadmill was not in use by anyone else and had not been paused. I suffered extensive injury to my right thigh as I landed full weight onto the hard left side of the treadmill