I highly doubt the people involved in this incident were either Olympic athletes, or willed firearms from a deceased handgun owner.They are not illegal, anyone who has a valid permit can still own or aquire one.
Legal firearms ae rarely used to commit criminal acts.
https://www.dunnandassociates.ca/news/legally-registered-guns-rarely-used-to-commit-criminal-acts/
There are hoops to jump through but you can still buy them.
You are confusing prohibited with illegal.
From the RCMP website.
Handguns
Changes to the Firearms Act impact licensed individuals who own, or who wish to acquire, handguns.
- Aspiring owners: If you want to acquire a handgun from any source in Canada, or through importation, you must meet one of the exemptions specified in the Firearms Act. Specifically, you must either:
- hold an authorization to carry in respect of a handgun; or
- meet the prescribed criteria and annually provide a letter to a chief firearms officer from a provincial or national sport shooting governing body indicating
- that you are training, competing or coaching in a handgun shooting discipline that is on the programme of the International Olympic Committee or the International Paralympic Committee,
- the disciplines in which you train, compete or coach, and
- that the handgun in question is necessary for training, competing or coaching in those disciplines.
- Current owners: Individuals who already own registered handguns:
- may continue to possess and use them.
- may dispose of them by:
- transferring them to an individual who meets one of the above exemptions;
- transferring them to a licenced business or museum;
- lawfully exporting them (see Exporting firearms to another country);
- having them permanently and irreversibly deactivated; or,
- surrendering them to a chief firearms officer, a firearms officer, or a law enforcement officer for destruction without compensation.
- Businesses: Authorized businesses may continue to sell handguns to exempted individuals, law enforcement and the military, or to other authorized businesses, including museums.
- Estates of deceased handgun owners: Handguns registered to a deceased individual may be disposed of by the same methods that are available to current owners. Please see the Transfer of firearms from estates page for further information.