The Technical Standards and Safety Authority (TSSA) says a truck driver at Sunrise Propane was caught engaging in banned truck-to-truck propane transfers prior to the explosion at its Murray Road facility two weeks ago.

The TSSA cited Sunrise for the same violations two years ago.

The practice of transferring propane directly from one tanker truck to another is prohibited in Ontario because it is said to increase the risk of a gas leak or fire.

"It's very clear that for a long period of time there may have been people in different parts of this province, right here and elsewhere, who were at risk and whose safety was in peril because the TSSA was asleep at the switch," Ontario Progressive Conservative Leader John Tory told reporters Friday while touring the Murray Road site.

An investigation by the TSSA has closed three Sunrise Propane sites.

Two of the three sites ordered closed are in Toronto, while another is in Mississauga, Ont.

The investigation further found that the truck-to-truck practice was a "frequent and routine" operating practice at the facility, according to the TSSA.

"This decision was based on a thorough review of the information currently available and the immediate nature of the potential hazards associated with operations at those particular sites," John Marshall, Statuatory Director of TSSA's Fuels Safety Program said in a Thursday news release.

Six other propane facilities in Ontario were shut down as part of an extensive audit of propane sites that was prompted by the explosion.

Only one, on Evans Avenue in Etobicoke, remains closed.

Officials said Friday that 193 of the largest propane sites have been inspected. The rest of the province's 3,000 propane sites will be inspected by the end of the year.

Two people, including a firefighter, died in connection with the explosion at the Sunrise site in Toronto.

An unidentified body thought to be that of Sunrise employee Parminder Saini was discovered at the site and Toronto district fire chief Bob Leek died at the scene.

City of Toronto clean-up crews are expected to be finished their work in the neighbourhood affected by the blast by the weekend.

With a report from CTV Toronto's Paul Bliss and files from the Canadian Press