Horrible news. These doctors and marshalls are an amazing bunch of hero's and have the upmost of respect of the racers.
When I crashed at our first round, the corner marshall thought the worst, red flagged the race and was with me in about 30 seconds. Doc Walker, from his post half a track away, hopped on a scooter and arrived just over a minute after it happened and before the ambulance. Bloody awesome and hugely comforting when you're hurt.