OTTAWA — Prime Minister Justin Trudeau says Canadians "are shocked by the news of the horrific attack in Manchester."
Police in the English city say 19 people were killed and at least 50 injured by an explosion at a concert by American pop star Ariana Grande on Monday night.
Local authorities say they are treating the incident as a terrorist attack.
In a brief statement posted on Twitter, Trudeau asks Canadians to "keep the victims & their families in your thoughts."
Public Safety Minister Ralph Goodale earlier expressed concern over what he called "brutal attacks" in northern England.
He took to Twitter to say his thoughts and prayers are with the victims and their families and that all Canadians "stand firm'' with the British people.
Other Canadian politicians have also reacted to the incident, including federal NDP Leader Tom Mulcair.
He called the incident "devastating news," adding, "all our love to Manchester and everyone affected by this terrible attack."
Toronto Mayor John Tory said the city stands in solidarity with the people of Manchester while Ontario Premier Kathleen Wynne also said in a tweet that she is "horrified" by the loss of life in the British city.
There was no immediate word of any Canadians among the victims.
Ottawa is advising Canadians in the U.K. to avoid the affected area in Manchester. Global Affairs Canada said any Canadians in the English city who require emergency assistance should call toll-free at 00-800-2326-6831.
Manchester police say they are working with national police and intelligence agencies to gather information about the incident.