If your talking F1, look up the Tom price 1977 Fatal accident and the steward crossing the road on youtube.
Yeah, seen that one, but it's difficult to get good footage. Basically, for those who don't know, two stewards with fire extinguishers run across the track to put out a burning car. Second steward across get's hit by Tom Pryce's car shattering him to bits and the extinguisher smashes Pryce's head killing him instantly and his car goes off down the track at full speed and smashes into a wall.
Bad accident, I would have to say if i was gonna run across a F1 tract it would be as fast as I could, the 1st steward wasn't exactly rushing either!