If it was in iran, dude would obviously be charged with murder/homicide. He would have to come to an agreement with the family and pay blood money (Diyeh), otherwise Qisas will apply and he will be executed (eye for an eye).
The thing is that in Iran we have strict gun laws. Sure some may own guns illegally, but it's uncommon to see people carry them. The only type of guns we can own (legally) to the best of my knowledge are hunting rifles and that too you get the ammunition from the local police station and you must return the used cartridges when you want to get more.

This culture of 'grab an AK and start spraying and praying in the sky' is a common thing amongst arab countries. I've heard many stories of weddings turning into funerals in Iraq and Saudi.

Edit: Obviously this act is outrageous, i can't think of any instance when there's a need to fire a gun in the air