Armed men in Halloween masks stole almost half a million dollars Thursday night in a robbery in Quebec.

Police say two men attacked two Garda security workers with pepper spray and took $431,000 from an armoured car at about 11 p.m. The thieves were armed with guns and wore Halloween masks.

The theft took place outside a Royal Bank branch at the Place Portobello shopping centre in the Montreal suburb of Brossard.

The two guards were taken to hospital after being pepper sprayed in the face. Neither was seriously injured.

Ghislain Vallieres of Longueuil Police said police will be reviewing security camera footage to find out more about the incident.

Police say they are unsure if the men worked alone or had other help. They are looking for witnesses to help in the investigation.

So far, the police haven’t released any descriptions of the suspects or vehicle they were driving. However, they seized an abandoned grey Dodge Caravan that was reported stolen in April. They are now trying to figure out if the vehicle was somehow connected to the theft.

'Strange situation'

Security analyst Chris Lewis told CTV News Channel that the information released so far is "sketchy" and may suggest that the guards were robbed outside of their car.

"It’s a strange situation in that normally only two guards get out of those armoured trucks. At least one stays inside, locked, and of course has got a radio and phone and additional weapons," Lewis said. "So if the guards had $400,000 plus on them and that’s what was taken that seems kind of odd to me in itself."

But, Lewis said, the lack of detail does not necessarily mean that the crime was an inside job.

"It looks different but that doesn’t mean that the guards were involved in any way. It may just be the police are withholding details," he said.

Lewis also said that the two guards would have been well-trained to deal with robbery situations.

Garda told CTV Montreal that it is co-operating with the police investigation, but did not share any more information.

The union representing Garda workers says the company should have three guards working on each truck, not two.

“The third worker on the truck sitting as a driver is the eyes of the people working inside,” union vice-president Guy Vaillancourt told CTV Montreal Friday. 

With a report from CTV Montreal’s Maya Johnson and files from the Canadian Press