The guards were servicing a Royal Bank at the Place Portobello shopping centre on Taschereau Boulevard when they were attacked by two individuals armed with guns and wearing Halloween masks.
Police found a stolen car parked at Brossard City Hall a few hours after the incident that they believe may be connected to the heist.
If the car is related to the crime, police say it suggests the suspects switched to another car and it indicates a high level of planning.
Police cordoned off the scene as they searched for evidence and investigators are looking into security camera footage of the attack.
The two guards were taken to hospital to be treated for pepper spray and shock.
Guard union calls for better security
The heist is renewing calls for improved security measures on armoured cars.
Angélique Paquette, president of Quebec's armoured car guard union, told Radio-Canada that the union had approached Quebec Public Security Minister Lise Thériault earlier this week to increase the number of guards required on deliveries to three.
"We're worried for our members' security, and the public's as well. As we've been saying for a long time, a third guard can make a big difference," she said.
A third guard would stay with the truck while the two other guards make a delivery.
"That guard can react and intervene," she said.