Earlier on Wednesday, a series of shootings in downtown Ottawa left a Canadian soldier dead.
Dozens of shots were reportedly fired, with police later confirming that incidents had occurred at the National War Memorial and on Parliament Hill.
The Maple Leafs released a statement following the postponement.
It read: "The Toronto Maple Leaf Hockey Club extends its deepest condolences to the family and friends of all affected by the tragic events in downtown Ottawa today.
"The club supports the National Hockey League's decision to postpone tonight's scheduled meeting with the Ottawa Senators.
"We have been witness today to some terrible events but are thankful to those brave men and women for their tireless service in protecting everyone's safety."
Senators owner Eugene Melnyk also released a statement, which read: "We are shocked and deeply saddened by today's tragic events on Parliament Hill and in downtown Ottawa.
"Our collective thoughts and prayers are with the families of the victims as well as with all Members of Parliament and staff who have had to manage through today's difficult circumstances.
"Hockey is certainly secondary to these type of tragic events and we know our fans stand alongside us with the league’s decision to postpone tonight's game."