I used to be an advisor for a fire Explorer post. It was, at the time it was shut down, the oldest continually chartered explorer post in the BSA, or so I was told.
One of the station tours we took the kids on was at the airport ARFF station. We went during our normal meeting time, so it was pretty dark out on the ramp. While the crew was demonstrating the roof turret for us, one of my kids, trying to get a picture, went too far forward and took a direct hit from about 40-50 feet away. The 'kid' in question was an 18 year old, adult-sized adult male. Nate got knocked off his feet and tossed a good 10 feet. He was scraped up, but not seriously hurt, and somehow managed to protect his camera and it wasn't damaged either. Yes, camera. It was camera years ago.
Our larger ( 2.5 inch) hoselines will push you back operating them, if you try to try to operate them standing up by yourself. Water's pretty heavy, and that hoseline flows about a ton of water a minute, at a pretty high velocity.