Officials at Husky Energy are still trying to determine the precise cause of an explosion and flash fire that ripped through a natural-gas well approximately 60 miles west of Edmonton, Alberta, British Columbia, on Monday, March 7. The exploratory well was being used to prospect for gas reserves through a technique called hydraulic fracturing, or “fracking,” in which fluids under pressure are injected into natural fissures within a gas formation to increase the rate of recovery. Thirteen contract workers suffered mostly burns; four workers remain hospitalized, one in serious condition. Husky spokeswoman Carla Yuill said the fire at the well