Irving Oil says a "major incident" happened at its oil refinery in Saint John, N.B., this morning.
Saint John police responded Monday morning, and they advised residents to avoid the area. Nearby streets have also been closed.
Refinery owner Irving Oil confirmed on Twitter that a "major incident" occurred there. "We are actively assessing the situation at this time and will share more information when available".
Fire crews have been called to the scene as pictures on social media show huge flames and plumes of smoke. But District Chief Mike Carr of Saint John fire said there were no air quality concerns, other than the smoke.
"I heard a loud bang that shook our house and rattled the windows", said Gordon Dalzell, who lives in Saint John near the refinery. "Praying for the safety of all involved".
Residents of the area described feeling an explosion shortly after 10 a.m., and noted that flames and smoke could be seen from a great distance.
The refinery is near several residential neighbourhoods about five kilometres from the city core, known as Uptown. "I heard a rumbling, roaring sound".
He said he and others saw a "very large black sooty plume of smoke" from their street.
He made a decision to drive by the refinery, and said he was nearby when he felt the vibrations of what he assumed must be a second explosion.
Michael Steeves said he was driving about a kilometre away when he saw flames reach as high as 100 feet in the air.
"We're sitting here and watching it burn right now".
Officials said all the plant's workers were accounted for after the fire, and four people received hospital treatment for minor injuries.