Flames are visible at the scene of a major explosion and fire at the Irving oil refinery in Saint John, New Brunswick October 8, 2018.

Irving Oil confirmed a "major incident" at Canada's largest refinery following reports of an explosion at the facility, a critical source of fuel for the U.S. Northeast market.

The explosion reportedly rocked the neighborhood around the Irving Oil refinery in Saint John, New Brunswick. It was not immediately clear what facilities at the plant were impacted.

@irvingoil: We can confirm that a major incident has occurred at our Saint John refinery this morning. We are actively assessing the situation at this time and will share more information when available.

The plant has the capacity to refine 320,000 barrels per day of gasoline, diesel heating oil, jet fuel and other petroleum products. Irving Oil exports more than half of that supply to the United States.

Photos of Irving's Saint John refinery posted to social media showed flames and black clouds against a blue sky. Residents reported that a blast shook homes.

The refinery employs 1,400 workers and is situated on a 780-acre plot in an area with "thousands" of neighbors, according to Irving Oil's website.

Irving Oil tweeted that all employees and contractors have been accounted for. Several contractors were being treated for non-life threatening injuries related to the incident, the company said.

@bmaguirens: My friend Jill just posted these photos of the St John's refinery in New Brunswick I hope everyone is ok Explosion shook her house

Crude oil and gasoline futures moved higher after the reports.

The refinery is likely the most important in terms of fuel imports to the U.S. Northeast market, according to Tom Kloza, global head of energy analysis at Oil Price Information Service.

"We probably import more gasoline from that single refinery than any other single refinery around the world," he said.

@DavidKellyNB: #Saintjohn emergency at the refinery. #NB

Irving Oil did not immediately return requests for comment.