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Emergency sirens across Dallas that blared over the course of more than an hour overnight were the result of a hacker who was able to access the city's system, city officials said Saturday.

Mayor Mike Rawlings called the hack "an attack on our emergency notification system." A city spokesman said all 156 emergency sirens were activated at 11:42 p.m. Friday, and the office of emergency management service agency eventually disabled the entire system at 1:17 a.m.

NBC Dallas-Fort Worth reported that the emergency sirens blared intermittently, and there was a surge of calls to 911. Confused residents took to social media to post video of the warnings with no apparent tornado or other emergency in sight.

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Dallas city spokesman Sana Syed wouldn't say how the hack was carried out, citing security reasons, but did say officials believe that it came from the Dallas area.

"We are putting in safeguards to ensure this type of hack does not happen again," Syed said in a statement.

Dallas Office of Emergency Management Director Rocky Vaz said investigators don’t believe any control systems or remote logins were involved.

"We have now pinpointed it to one area where we think they were able to get into our system and activate all the sirens, and put that into a mode where they sent signals for it to be activated over 60 times," Vaz said.

The OEM hopes to have the system back up and running, with safeguards to prevent another hack, by Sunday night.

Vaz said the office has other mass notification systems, like reverse 911 and social media, to inform the public about any emergencies, and are working with the Federal Emergency Management Agency to use its alert systems if necessary.

"We apologize for all the sirens that were going off last night, we did our very best. We shut it down as quickly as we could," Vaz said.

Rawlings said the city will prosecute anyone found to be behind the hack.