they were likely firing AK47s into the air as part of some "celebration". Next time, throw rice.
How insensitive. Don't you know that rice expands in the poor birds stomachs (or so they say) and that the politically correct item to throw is bird feed??? However, remember to unwrap the seed because somee brides have been hit in the eye with the heavy bag full of seeds - this really messes up the wedding photos.