Help with seagulls problem?

Okay so i need to get rid of some seagulls of my roof....Literally kill them....I know it is harsh and stuff but they have attacked my children twice leaving them with marks on there arms....both kids are 4 and 1 sooo pleaseeeee i tried baking soda...didnt do anything.....and i have even tried shooting them but it just did nothing and the pellet/bullet tingy just bounced of sooo anything pleasee i rather they died quickly with no pain??