A Cessna 560XL Citation Excel suffered a runway excursion after an aborted takeoff at Oroville Airport, California, USA. A fire broke out in the grass besides the aircraft. After all ten occupants had evacuated the aircraft, the fire spread and engulfed the aircraft. The pilot flying reported to the NTSB that prior to takeoff, they had a waypoint fix and departure change, which he updated within the flight management system. After some four minutes they taxied onto runway 2 and the captain called for the before takeoff checklist. Following completion of the checklist, they initiated takeoff, and the non-flying pilot called “airspeed alive,” V1, and Vr. The pilot flying pulled the yoke back but the airplane didn’t lift off. A second attempt had no effect. Shortly after, the non-flying pilot called for an abort, and the pilot flying applied full thrust reversers and maximum braking. Subsequently, the airplane exited the departure end of the runway, impacted a ditch, and skidded across a grass covered area, where the post impact fire ensued. Examination of the runway revealed tire transfer marks which originated from the runway 2 hold short line and progressed onto the runway, and continued throughout the entire length of the runway, overrun, adjacent runway, grassy area, taxiway, and grassy area near the main wreckage. Probable Cause: The pilot’s failure to release the parking brake before attempting to initiate the takeoff, which produced an unexpected retarding force and airplane nose down pitching moment. Also causal was the flight crew’s delayed decision to abort the takeoff, which resulted in a runway excursion. Contributing to the accident was the lack of a NO TAKEOFF annunciation warning that the parking brake was engaged, and lack of a checklist item to ensure the parking brake was fully released immediately before takeoff.