Computer hack sets off 156 emergency sirens across Dallas

Dallas' 156 sirens, normally used to warn of tornadoes and other dangerous weather, were triggered at 11:42 p.m. CDT on Friday.The wailing did not end until 1:17 a.m. CDT on Saturday when engineers manually shut down the sirens' radio system and repeaters, city Emergency Management Director Rocky Vaz said."At this point, we can tell you with a good deal of confidence that this was somebody outside of our system that got in there and activated our sirens," he told reporters.