Toronto police confirmed the hack took place, but offered no further details. The website has since been restored.
The cyberattack comes on the heels of similar hacks on the websites for the City of Ottawa, Ottawa police and the Supreme Court of Canada over the weekend.
For about an hour on Friday, the City of Ottawa’s website displayed the name of an Ottawa police officer involved in the investigation of an area teen who allegedly called in fake emergencies across North America, prompting police departments to deploy SWAT teams. The practice is often called “swatting.” The name appeared beside a cartoon dancing banana.
The City of Ottawa and the Supreme Court of Canada websites were back running by Sunday, but the Ottawa Police Service site remained offline as of Monday morning.
A Twitter user who goes by the name @AerithTOR has claimed responsibility for all four incidents.
The user appears to be based in Turkey and claims to have connections to international "hacktivist" syndicate Anonymous, though CBC News could not confirm any connection.
The account has been suspended from Twitter.
The user has also posted a message to an online forum threatening to hack the Conservative Party of Canada and the Parliament of Canada websites.