The accident happened when welding was being carried out on condensate tanks, Encana said.
All five of the injured were contractors, Encana added.
One of the victims was said to be in a critical condition and was air-lifted off site.
The tank explosion occurred at the Antelope 91-29H facility, near Pinedale, on Friday morning.
“We know that some welding work was being conducted on the condensate tanks on location.
