What can I do about a neighbor that made a single family residence into a multi family without permits? 11 people reside in home

Our neighbor is from El Salvadore and is not considerate of neighbors, he has at least 11 vehicles including heavy equipment that is parked in front of our home. He also took out the sidewalks to make his driveway larger. We had a very nasty incident at 4th of July that endangered children ( he threw an M500 in the air and it landed in our yard) next to the children. I confronted him on it and the next thing I know I am being harrassed everyday by the women who are there calling me a nasty spanish words. I want to be legal about all this and I need help.