The explosion at the Valero Energy refinery in Port Arthur, Texas has been confirmed to be caused by a heater, with no foul play involved, according to the Jefferson County Sheriff's office.
The fire, which occurred on Monday at 7:22pm local time, sent thick black smoke skyward and prompted a shelter-in-place order for west Port Arthur residents, but fortunately resulted in no injuries and all personnel were accounted for.
Although the investigation is still underway, preliminary reports state that the fire was caused by the explosion in a diesel hydrotreater, with Valero Energy officials shutting down the refinery to prevent further fueling of the fire.
Valero and local authorities have assured that there is 'no concern' with the air quality, with Jefferson County Judge Jeff Branick stating that air monitoring did not indicate exceedances of safe thresholds.
