Investigators at the site of the Sunrise Propane facility on Murray Road say they may have a possible cause for the explosion that saw an entire neighbourhood evacuated.

A statement from the Director of the Technical Standards and Safety Authority says a driver was engaged in a truck-to-truck transfer of propane prior to the blast. Such actions are not allowed in Ontario for safety reasons.

Yesterday evening, the TSSA suspended the licenses of the three Sunrise locations across the GTA in wake of the August 10 blast at the company's Downsview location.

They include the Murray Road location as well as sites located at 1201 Dundas Street East in Toronto and 3171 Derry Road East in Mississauga.

Sunrise Propane license holders at these sites were served with a formal "notice of the director's proposal" to revoke their licences to operate propane filling stations. The action results in the immediate shutdown of operations.

The sites could be closed for good, barring any successful appeals by the company owners. They were closed due to issues relating to the operation of the facilities, says Dave Lisle of the TSSA, adding they will be "sealed and secured" to ensure safety.

Meanwhile, the first part of an inspection blitz of 193 propane facilities in the province was completed on Friday.

Officials have issued "cease and desist" orders to seven large propane sites in the province -- including two in the GTA, which remain closed. Five of these sites are operational right now.

Propane sites in Kitchener, Waterloo, Cornwall and Ottawa have also been ordered to close.

An official with the TSSA says infractions at the sites include untrained staff and faulty equipment. Three of the sites have now re-opened with a fourth site hoping to resume operations today.

Cleanup finishes

The city's asbestos cleanup around the site of the propane blast was also finished on Friday.

On Saturday, crews will be back in the Keele Street and Wilson Avenue area for a final visual inspection.

All air quality tests are expected to be finished by Monday, and so far, all have indicated that the area is safe.