IRVING, Texas -- A 16-year-old boy has died from his injuries after he was attacked by three pit bulls on Saturday in Irving, Texas.Police say the dogs were in a fenced off area of a yard. Authorities don't know what the teenager was doing in the backyard, saying that he didn't live at the home.Neighbor Elizabeth Cantu said she heard screams just before 5 a.m. She climbed onto her truck, looked into the backyard and saw the pit bulls attacking the teen, who was desperately knocking on the door.She said she honked her horn to try to wake her neighbor, who never responded, and called 911.Three officers jumped the fence and tried to get between the victim and the dogs. One officer was bitten. Police had to shoot one dog, and put the other two in quarantine.The 16-year-old was taken to the hospital, where he later died.The dogs' owner Guillermo Lorenzo said the dogs did their job because he believes he was being robbed."It's what dogs are supposed to do. Why am I going to have a little Chihuahua when somebody comes, and they're going to kick the door? No," Lorenzo said.Cantu said the boy was bitten everywhere, on his neck, arms and legs."No one should go through what he went through," Cantu said.