CHICAGO - Thirteen people have been killed and at least 54 others injured in shootings across Chicago so far over the Fourth of July weekend.Nine of the weekend’s victims were minors, and two of the children died from their injuries.A 14-year-old boy was among four people killed in a shooting that wounded four others Saturday night in Englewood on the South Side.They were at a large gathering in the street about 11:35 p.m.