Authorities say a 10-year-old Iowa boy died after he was badly burned while using gasoline to make a backyard fire with his older brother.The incident happened in the family's backyard on Saturday near Earlham about 30 miles west of Des Moines. The Madison County Sheriff's office says Chris Allsup and his 13-year-old brother started a fire with gasoline from the garage. At some point, Allsup poured the rest of the gas on the fire, and the flames engulfed him. Allsup sustained burns on 91 percent of his body. He was flown to Iowa City for treatment but didn't survive.