Friend went into shock?!

today at my school was not a real school day. it was just sports and games all day long. one kid 2 years younger than me hurt his knee during 3 legged soccer. i wasnt in that gym at the time so i didnt see what happened but i went in a few minutes later. the kid was laying on the floor, there were 2 or 3 teachers/coaches around him and paramedics were coming in. i couldnt see that much but i think his legs were kind of spread out. i heard from other kids that he probably dislocated his knee but i dont know. i guess he had some type of injury to the knee though.
my 15 year old brother and sister and cousin are all best friends with him so they were down there with him on the floor.
the paramedics put him on the stretcher, we all clapped(why do we clap when someone goes on the stretcher?)
He is kind of my friend too so i i am going to see him in a little while tonight with my 2 siblings and cousin. What kind of things will he be hooked up to? will he have an IV? will he be tired or anything like that? how long will he be in the hospital or have to take it easy at home? how did he go into shock from a knee injury? he was whitish blueish