Prime Minister Justin Trudeau is condemning what he is calling a deadly terrorist attack in the French city of Nice.

French authorities say an attacker armed with a knife killed three people at a church in the Mediterranean city Thursday, prompting the country to raise its security alert status to the highest level.

Trudeau says in a Twitter post that Canada stands in solidarity with the French people and denounces the attack as unjustifiable, adding his thoughts are with the loved ones of the victims.

Bloc Québécois Leader Yves-François Blanchet called on Trudeau to issue a strong condemnation of the attacks, arguing the prime minister has not been forceful enough in denouncing previous ones.

Thursday's incident was the third attack in two months in France that authorities have attributed to Muslim extremists, including the beheading of a teacher.

It comes amid a growing furor over caricatures of the Prophet Muhammad that were republished by the satirical newspaper Charlie Hebdo renewing vociferous debate in France and the Muslim world over the depictions that Muslims consider offensive but are protected by French free speech laws.