RANCHO CORDOVA - Federal investigators say a utility company used a wrong pipe to repair a gas line, leading to a deadly house explosion in a Sacramento suburb last year.

The National Transportation Safety Board released initial findings Thursday about the explosion of a house in Rancho Cordova on Christmas Eve 2008. The blast killed 72-year-old Wilbert Paana and injured five others.

Two homes on either side were also damaged.

Investigators found that Pacific Gas & Electric Co., the utility that supplies natural gas to the area, used a packing pipe not approved for gas line repairs in September 2006. A final report is still being completed.

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PG&E spokesman Brian Swanson says the utility has taken extraordinary measures to ensure such a blast never happens again. The utility says it has also made policy changes.