1997 Volvo 850 Starter won't stop

I was pulling into my driveway and I heard a loud grinding noise. When I stopped and turned off the engine, the grinding noise stopped, but the starter continued to run. Disconnecting the battery stopped the starter, but when reconnecting the battery, I hear a click (I'm assuming the solenoid) and the starter starts and continues to run. I tried disconnecting the ignition switch, but still the same problem.