A mysterious mass sounding of emergency sirens in a densely-packed US city saw social media light up with conspiracy theories.
More than 150 emergency sirens were set off in Dallas yesterday sparking terror among citizens about impending doom.
People took to Twitter as wailing sirens blasted through the night on Friday and into Saturday morning.
All 156 outdoor tornado warning sirens – meant to alert the 1.3 million Dallas residents of impending disaster – went off at once across the city.
The sirens, which began at 11:44pm, did not stop until 1.20am.
People discussed theories about the cause, from the start of a Russian invasion to a disease epidemic.
Others compared the haunting sound to the siren featured in the apocalyptic movie franchise The Purge, where murder is legal for 24 hours.
A fan of the movies said: “Can the Purge please wait until tomorrow, I’m so tired at the moment.”
One person tweeted: “There is no way this is an accident. I’ve lived here for 43 years and never experienced this.”
Another said: “In case you were wondering what the end of the world sounds like, it’s every tornado siren in the entire city of Dallas going off at once.”
City officials rejected allegations that the sirens were malfunctioning or were intended to signal disaster.
Instead, according to the City of Dallas Office of Emergency Management, the siren system had been hacked.
A spokesman said: “It does appear at this time that it was a hack, and we do believe that this came from the Dallas area.
“We can’t talk a whole lot about the hack itself, because obviously, we don’t want this to happen again.”
The city officials were forced to unplug the entire emergency system to put a stop to the sirens.
City spokeswoman Sana Syed said: “We had people asking if we were being attacked because of what’s going on overseas.”
She said that city officials had about 4,400 911 calls from about 11:30 pm on Friday to about 3am on Saturday.
Emergency services have since been relying on 911 and social media for emergency calls.
Officials hope to have the alert system back up and running by Sunday night or Monday afternoon.