Residents of Dallas received an unwelcome scare Friday night after hackers managed to access the city’s emergency system and set off all of the city’s warning sirens.

The hack saw all 156 of the city’s emergency sirens go off between 11:40 p.m. Friday and 1:20 a.m. Saturday, causing fear and confusion, not to mention keeping residents awake and making a flood of 911 emergency calls, according to the New York Times. The sirens, a regular installation in many American towns and cities, are normally used to warn of tornadoes and other dangerous weather, meaning that residents hearing them may have thought they were at risk.

In an interview with reporters posted to Facebook, Dallas Public Information Office Director Sana Syed confirmed the number of sirens activated and said that “it does appear at this time that it was a hack, and we do believe that this came from the Dallas area.” While giving no further details as to the nature of the hack, the suggestion that it may have happened in the Dallas area may suggest that physical access to the emergency network was obtained versus remote attack over the Internet.

Emergency Management Director Rocky Vaz contradicted that, telling reporters separately that “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.”

Given that the form of the hack was not immediately clear, the city took the entire network offline and will instead rely on local media, 911 phone calls and the federal radio alert system until the network is restored. At the time of writing, the city expected the system to be back up and running, presumingly hacker-free, by late Sunday.

The hack is being investigated by system engineers who have contact the Federal Communications Commission. But authorities such as local police and the Federal Bureau of Investigation are said not to be involved yet despite what would appear to be a criminal act of hacking.

Photo: FEMA/Wikimedia Commons