TORONTO -- Prime Minister Justin Trudeau says a Canadian was among those killed in Saturday night's terror attack in London.

In a written statement released Sunday, Trudeau says the government will not be commenting further out of respect for the family.

Earlier, the High Commission of Canada in the United Kingdom confirmed that a Canadian was "directly impacted" by the attack.

The attack began at about 10 p.m. local time when police and witnesses say a white van barrelled into pedestrians on London Bridge.

The Canadian government is advising citizens to be vigilant in the wake of the attack.

The government and diplomats on the ground in London are advising travellers to avoid the affected areas, follow the instructions of local authorities and monitor local media.

Trudeau says he's heartbroken that a Canadian was killed.

"We grieve with the families and friends of those who have lost loved ones, and wish all those injured a speedy and full recovery," he said in the statement.

On Saturday, Conservative leader Andrew Scheer tweeted that he was "horrified by the events in London" and that Canada would always stand with the people of London.

Ontario Premier Kathleen Wynne said in a tweet Saturday that Canadian hearts were heavy with the news of the violence in London.

Officials in the U.K. say that after the van hit pedestrians on the bridge, three men armed with large knives then fled the scene and started attacking people at bars and restaurants in the nearby Borough Market.

Police said seven people were killed and at least 48 others were wounded, some critically, before officers shot and killed the three suspected assailants.

The violence turned a warm spring night in an area packed with revellers into a scene of panic and chaos, with officers running through crowded streets screaming for people to flee.

--With files from The Associated Press