Quebec’s power utility says its website and mobile application have been knocked offline by a cyberattack.

Hydro-Québec says 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.

The utility says the attack has shut down its website and cellphone application but says its critical systems are not affected.

Hydro also says there was no data breach and personal data was not compromised.

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.

As of 10:30 a.m. neither Hydro-Québec’s website nor its mobile app were operational.