WATCH: Explosion rocks oil refinery in Saint John, New Brunswick

Emergency measures officials say four people suffered minor injuries from the massive oil refinery explosion that shook Saint John, N.B., this morning.

The explosion at an Irving Oil refinery on the city's eastern side set a fire and sent thick, black smoke pouring into the air.

Residents of the area described feeling an explosion shortly after 10:15 a.m., and noted that flames and smoke could be seen from a great distance.

The blast happened in a diesel unit, requiring everything to be shut down.

A local hospital had issued an ``orange alert,'' meaning it was preparing for a possible influx of patients, while the City of Saint John advised residents to shelter in place.

In a news conference, officials said at no time was there any threat of the fire spreading from the initial area, and the air quality in the surrounding region was not compromised. They said the situation has been stabilized and everyone had been accounted for.

Irving Oil's chief refining officer Kevin Scott says staff members and firefighters were still dousing the facility with water Monday afternoon in an effort to prevent the flames from sparking back up.

WARNING: SOME OF THE LANGUAGE ON THIS VIDEO IS GRAPHIC

- With files from NEWSTALK1010