A spokesperson for the Ontario Ministry of Labour says an arc flash caused Sunday's explosion at a warehouse on Malden Rd.
Four workers were on site performing an upgrade to the electrical system at Wolverine Warehousing and Distributing Ltd. around 2pm. Two were working on an electrical panel, and a third was conducting a phase-out test with a meter when there was an arc flash.
Two of the workers were sent to the hospital with serious burns on their upper bodies, while the third suffered minor injuries. A fourth worker was not injured.
The ministry, along with investigators from the Office of the Ontario Fire Marshal, is continuing its investigation.