TORONTO -- The Air Canada Centre stood up and sang in solidarity Saturday to honour two soldiers killed in separate incidents.

The crowd was an enthusiastic part of a co-ordinated rendition of "O Canada" with the Canadian Tire Centre in Ottawa and Bell Centre in Montreal.

PA announcer Andy Frost called the pre-game ceremony before the Maple Leafs-Bruins contest "a show of solidarity and strength."

"We may battle in arenas and on ice but tonight we stand together," said Frost.

Photos of Cpl. Nathan Cirillo and Warrant Officer Patrice Vincent were shown on the top of the scoreboard as the anthems from Ottawa were shown on the big screen with both the Leafs and Bruins lined up at their blue-lines.

The biggest roar came when the Canadian flag was shown on the big screen after the anthems.

Cirillo died Wednesday after being shot by a lone gunman at the National War Memorial in Ottawa. The 24-year-old Argyll soldier, who will be honoured Tuesday at a regimental funeral in Hamilton, was working sentry duty at the time.

Vincent was killed in a separate incident Monday in Saint-Jean-sur-Richelieu, near Montreal, when a man deliberately drove a car into him and another soldier in the parking lot of a federal building.

Vincent, 53, was a 28-year-veteran of the military.

Two members of Cirillo's Argyll and Sutherland Highlanders of Canada's regiment and a member of the Royal Canadian Air Force stood at centre ice as part of the Leafs' pre-game tribute.

"From Leafs Nation, we thank you," said Frost.

The Leafs were staying at a hotel across the street from the violence in Ottawa. Some were sleeping when the first shot was fired. Head coach Randy Carlyle was walking through the nearby Rideau Centre mall when the order to evacuate came over the PA system.

The hockey team left town in the afternoon after the NHL called off the game.

For the Bruins, the evening was nothing new, sadly. Their home was rocked by the Boston marathon bombing in April 2013, prompting the league to cancel a game with the visiting Ottawa Senators. Bruins coach Claude Julien is from Ottawa.

The Leafs have a tradition of honouring the military.

Joffrey Lupul's "Lupe's Troops" program has shed a spotlight on a soldier at every home game since January 2013, with the Leafs winger donating two tickets and jerseys to each Canadian Forces member selected.

The program began in 2009 as "Luke's Troops" under former Leafs defenceman Luke Schenn.

A message from Lupul was shown on the scoreboard towards the end of the first period before the latest member of "Lupe's Troops," Capt. Ronald Frobel, was introduced.

"Thank you to our troops for the sacrifices they make so we can enjoy a better life," said Lupul.