Sunoco Inc. (SUN) said Monday evening that the fluid catalytic cracking unit at its Marcus Hook, Pa. refinery was shut down following an explosion.

The refinery is running at 85% of planned rates, company spokesman Thomas Golembeski said. The refinery hadn't been running at full capacity prior to the explosion because of economic conditions.

The fire is still buring but is contained, Golembeski said.

-By Susan Daker, Dow Jones Newswires; 713-547-9208; susan.daker@dowjones.com