It was part of an organized competition called "Field Day" which was resurrected this year after having been squashed 15 years ago due to a big brawl between the participants. In this event, a relay race, the first firefighter puts on all his gear and runs 50 yards. The next one hurdles a window cutout. The next drags a full weight test dummy, the next rolls up a section of hose, the next unrolls the hose and attaches it to the fire engine, the next runs to the end of that length of hose and attaches a nozzle and shoots a target.
It's fun and there are ways to gain time, one way is to call for water to the hose before the nozzle is fully attached, which is a VERY dangerous gambit and is technically against the rules I think. In this case it was not done as a 'cheat' but due to inexperience, this team only had the bare minimum of attendees to attempt the event and they had never practiced it, and this firefighter called for water before he was ready to handle it, and when the hose charged the nozzle was not secure in his hands and he wound up doing what you see in the picture and was very lucky he was not hurt.