UPDATE 3-Irving Oil shuts Saint John, Canada refinery after fire

(Adds details on explosion, injuries, hospital statement, paragraphs 4-8)

Oct 8 (Reuters) - Irving Oil Corp shut its Saint John refinery in the Canadian province of New Brunswick on Monday morning after a fire, with photos showing smoke billowing from the complex.

The company said it was dealing with a "major incident" at the 320,000 barrel-per-day refinery. Residents reported hearing an explosion and seeing a fire, according to local media.

"We are actively assessing the situation at this time and will share more information when available," Irving said in a statement. The company did not respond to a request for further comment.

There were only a couple of "minor injuries" as a result of the explosion, according to local media. Horizon Health, which operates the Saint John Regional Hospital, said on Twitter it was on high alert, but a spokesperson there declined to comment further.

Energy intelligence service Genscape reported the plant was being shut due to a fire, saying it appeared to have occurred near the catalytic reformer.

The crude section, catalytic reformer and a cogeneration unit were shut following the incident, Genscape reported, adding that multiple units were already offline for maintenance.

The company shut most of the plant for planned maintenance in late September, but the smaller, 25,000 bpd gasoline-making units and the 125,000 bpd crude unit were still running, a source familiar with the plants operations said.

The source said he believed the explosion was within the section of the plant that houses the hydrogen unit.

Over one-half of the finished products from the refinery are exported to the U.S. Northeast, according to Irving's website.

Reports of the fire sparked a rally in futures in refined products; gasoline was up about 2 percent following the reports. (Reporting by Jarrett Renshaw in New York and Eileen Soreng and Subrat Patnaik in Bengaluru; Editing by Chizu Nomiyama, Jeffrey Benkoe and David Gregorio)