DALLAS -- The City of Dallas confirmed an apparent hacking triggered emergency sirens to sound across the Dallas area Friday night into early Saturday morning. 

In a brief news conference, Rocky Vaz, the city's emergency management director, called it a rare incident. Earlier, the city reported the system had malfunctioned.

Although the city says it determined how the system was hacked, they continue to investigate who did it. 

"For security reasons, we cannot discuss the details of how this was done, but we do believe that the hack came from the Dallas area. We have notified the FCC for assistance in identifying the source of this hack. We are putting in safeguards to ensure this type of hack does not happen again," the city said in a news release. 

All of the 156 outdoor warning sirens in the city of Dallas went off, the first one happened at about 11:42 p.m. The sounds kept many residents awake and concerned. Other surrounding cities' sirens did not go off despite earlier reports, the city said. 

WFAA viewers began reporting the sirens at around 11:44 p.m. Friday.

According to Dallas PIO director Sana Syed, there was no emergency or weather alert. 

Crews worked to manually shut down the sirens, but warned it could take up to 3 hours for a complete shutdown to occur, according to a city statement.  

WFAA viewers reported sirens sounding in other communities besides Dallas. Officials urged residents not to call 911. 

Surrounding cities also reported hearing sirens, but officials confirmed only the sirens in Dallas were triggered. Later Saturday morning, Garland Police sent out a tweet to clarify the situation.

"The city of Garland has determined that it's outdoor warning sirens did not sound during the night last night. We had no malfunction." — Garland Police PIO (@GarlandPD) April 8, 2017

The city also reminded residents that they may hear sirens again as engineers determine if the system is functioning properly. "Right now, our priority is to work on reactivating our system. We won’t know the health of our sirens until we reactivate the system.  We ask residents to be patient with us in case the sirens sound again during re-activation and please do not call 911 or 311 for concerns about sirens," the city said in a news release. 

Dallas Mayor Mike Rawlings described the incident as "an attack on our emergency notification system." Mayor Rawlings posted on his Facebook page about the need for a better security infrastructure. 

"This is yet another serious example of the need for us to upgrade and better safeguard our city’s technology infrastructure. It’s a costly proposition, which is why every dollar of taxpayer money must be spent with critical needs such as this in mind. Making the necessary improvements is imperative for the safety of our citizens," Mayor Rawlings said.