The BBC reports the fire began Monday as an explosion in the refinery's liquefied petroleum gas unit, with various reports the unit, recently repaired, was completely destroyed.

The refinery itself is still operating, according to an engineer there. Located 120 miles north of Baghdad, Baiji is an important crux in Iraq's oil sector, as well as a hotspot for insurgent activity.

Pipelines from Kirkuk, one of Iraq's largest and oldest oil fields, feed a pipeline to Baiji to refine crude. And it's at Baiji where another set of pipelines turns north to send oil exports to Turkey.

The pipelines to and from Baiji have regularly come under attack since 2003, though lately there has been a reduction in successful or damaging hits.

The BBC reports at least one person killed and a number of injured in the explosion and blaze, which lasted two hours.