An 11-year-old boy is hospitalized with severe burns after a backyard bonfire exploded Monday evening in South Jersey, officials said. Emergency crews responded to a home on the 200 block of Ramblewood Parkway in Mount Laurel Township around 6:15 p.m. after neighbors reported an explosion. A preliminary investigation determined that the child poured gasoline on the already burning fire and that the flames traveled up the stream to the gas can, which exploded while the boy was holding it, according to Mount Laurel Police Department spokesman Kyle Gardner. The child was airlifted to St. Christop…