Hackers cracked into the systems managing the public emergency alarms in Dallas, Texas, and set off all 156, repeatedly, on Friday night - apparently for a joke.
The attacker who cracked the computer control systems set the alarms to repeat 60 times during the night. The first wave was at 11.42pm on Friday night and it wasn't until 1.17an on Saturday that authorities managed to stop the din.
And emergency services were - not surprisingly - inundated with calls as a result.
Rocky Vaz, the director of Dallas Office of Emergency Management, claimed that the hacker was definitely local, but admitted that he or she hasn't been found yet.
Although the sounding of the sirens may have seemed like a harmless and rather annoying prank, there's a lot of issues at stake here.
Firstly, the sirens are usually used to warn citizens of impending natural disasters, such as tornados and earthquakes, meaning that citizens need to have complete faith in the system or it won't be as effective if there's a real need for evacuation.
Then, of course, there's the small fact that it did scare the bejesus out of citizens who then called 911 in droves, blocking the system as a result, taking down access to the services to people with genuine emergencies.
USA Today reports that, at one point, callers were being put on hold for six minutes at a time - enough to kill someone undergoing a serious heart attack. The usual response time is more like 10 seconds.
Dallas spokesperson Sana Syed said the 911 system received more than 4,400 calls in the four-hour period between 11.30pm and 3.00am, twice the number they would normally expect in that eight hour period. And, given the sirens were only going off for the first couple of hours, that means the concentration around midnight was likely even higher.
Facebook told by Brussels-based court to stop tracking non-users and to delete all data held on them
Supply chain and manufacturing experience could give Dyson an important edge
New VR Zone Portal arcades open in London and Tunbridge Wells
Systems-on-a-chip with integrated AI features could make voice and facial recognition