Crewman falls off roof during freak pop up storm

I was doing a roof job in Dallas when I noticed the sky getting dark in the distance. I instructed my crew to dry in and seal up the roof we were working on and to come down until the storm passed. Nothing worse to a roofer than rain while you have a roof opened up. I noticed a different crew doing a roof job a block away from my job. I jumped in my truck to go see if the other crew had prepared ahead of time. They had not done so and this is what happened next.