Story highlights TV5Monde went black late Wednesday and was still out hours later

The network blames an "Islamist group"; there's no claim of responsibility

(CNN) Eleven channels associated with the French-language global television network TV5Monde went black late Wednesday due to an "extremely powerful cyberattack," the network's director said.

In addition to its 11 channels, TV5Monde also temporarily lost control of its social media outlets and its websites, director Yves Bigot said in a video message posted later on Facebook.

On a mobile site, which was still active, the network said it was "hacked by an Islamist group." ISIS logos and markings could be seen on some TV5Monde social media accounts.

But there was no immediate claim of responsibility by ISIS or any other group.

The outage began around 10 p.m. Paris time (4 p.m. ET), and network teams were still working to restore service more than five hours later.

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