The U.S. Chemical Safety Board (www.chemsafety.gov) is investigating the second explosion this year at a Utah oil refinery, according to a report by the Associated Press (www.ap.org). The blast damaged 10 nearby homes, one of which was deemed structurally unsound by a building inspector.

The refinery, located in Woods Cross, Utah, had fires in 2003, 2005 and 2007, according to federal records. The explosion was reportedly started in a diesel hydrotreater, which removes sulfur compounds from diesel fuel.

On Jan. 12, four people were seriously burned at prior explosion a the same refinery when a 440,000 gallon storage tank caught fire and burned for 11 hours, according to the Associated Press.

For the full Associated Press report on this story, click here.