A hacker, or group of hackers, has set off all 156 tornado sirens in the city of Dallas, Texas, on the night between Friday and Saturday, April 7 and 8.
The alarms started shortly before midnight, at around 11:45 PM, local time, and were heard in twelve waves, before authorities shut down the entire system at around 01:20 AM.
Officials from the Dallas Office of Emergency Management said this wasn't a malfunction, and someone was intentionally setting off the sirens on purpose. They also excluded this as the work of an insider and called the incident a hack.
"What we have learned since last night [is that] it woke up a lot of people. All 156 sirens in the city were activated last night," said a city official in a video posted online. "It does appear at this time that it was a hack and we do believe that this came from Dallas area."
Authorities installed the sirens all over the city to serve as a warning system for natural calamities. The sirens have been used primarily for warning the population against tornadoes.
Officials said they kept stopping the alarms, but the intruder kept restarting the sirens. Eventually, they shut down the entire alarm system as they couldn't keep the attacker out. Officials rebooted the alarm system earlier today, Sunday, but they plan to carry out tests and an investigation on Monday.
Many Dallas residents flooded the 911 emergency system with phone calls attempting to inquire about what was happening. Despite pleas from the media and authorities to stop calling unless they had a real emergency, the 911 system received over 4,400 calls, with 800 callers in the waiting queue during peak call volume.
The Dallas Office of Emergency Management said it filed a complaint with the FCC. Below is a video recorded on the night of the incident.