On lap 22, a 19 year old marshall, Frederik Jansen Van Vuuren, crossed the track to extinguish a fire on Renzo Zorzi's retired Shadow during racing conditions and was struck by Tom Pryce's Shadow at high speed. The impact killed both Pryce and Van Vuuren instantly: Van Vuuren from the impact of the collision, Pryce due to head injuries inflicted by the fire extinguisher that Van Vuuren was carrying. The impact from the fire extinguisher ripped Pryce's helmet from his head, causing the chin strap to nearly decapitate the unfortunate Welshman. Pryce's car continued on down the main straight with his helmetless body still in the cockpit until it finally left the track at the first corner, taking the Ligier of Jacques Laffite out of the race in the process.
The sport reacted with genuine sorrow at the loss of two young men. Tyrrell mechanic Trevor Foster viewed the incident from a distance, later recalling; "I can remember quite vividly [Pryce's] teammate's car had already pulled off to the side of the track and it had started a small fire. Then the next thing I can remember is seeing Tom's car coming down the straight. I can almost remember now a momentary lift of the throttle much earlier than you would have expected and I looked and I saw something fly up from the car, which tragically turned out to be the marshal." [1] Elsewhere, David Tremayne, a veteran biographer and journalist, recalled the feelings of disbelief and horror following the aftermath of the incident; "The tragedy itself - the sheer randomness of it - is so hard to take and still is. You tend to focus your anger on someone and for a long time it would be focused on a 19 year old kid, called Jansen van Vuuren, who ran across the track."
The event was captured on film and was included in the motor racing film One by One.