Quebec's power utility said Thursday it was working to get its website and mobile application running again after they were knocked offline by a cyberattack, for which a pro-Russian hacker group claimed responsibility.

Hydro-Québec said it was targeted at around 3 a.m. by a denial-of-service assault — when attackers flood an internet server with traffic and overwhelm it, triggering a crash.

A spokesman for the province-owned utility said that while the attack shut down the company's website and cellphone application, critical systems were not affected. 

"It did not affect our production, transmission and distribution of electricity," Francis Labbé said in an interview, adding that personal data was not compromised.

As an analogy, the Hydro spokesman compared the situation to people demonstrating in front of a building without taking anything inside.

"They did not take any information from us," Labbé said. "It's an attack on our website that make it unavailable for our customers, unfortunately."

In recent days, Canadian websites have been targeted by cyberattacks with pro-Russian groups claiming responsibility. Targets included websites for Prime Minister Justin Trudeau, the Port of Québec and Laurentian Bank.

On Tuesday, Trudeau said it was not uncommon for Russian hackers to target nations that support Ukraine in its war against Russia, particularly when countries host high-level Ukrainian delegations — as Canada did earlier this week.

A pro-Russian hacker group known as NoName057 (16) claimed responsibility for the Hydro-Québec attack. The hacker group, which has reportedly acted on Moscow’s orders, has taken part in a slew of cyberattacks on the U.S. and its allies in the past. 

"We saw a tweet of an organization that wanted to take responsibility for that attack," Labbé said. "We will put our focus on getting everything back to normal and then we will make our inquiries."

Labbé said it's a reminder that these kinds of attacks are becoming more frequent. The utility has 300 people working on its information technology unit to restore the compromised website and mobile app. "We're working to get everything back as soon as possible, but it's very hard for us to tell you when exactly everything will be settled."

This report by The Canadian Press was first published April 13, 2023.

— With files from The Associated Press.