Investigators: Gas vented before explosion

RALEIGH They said their investigation was not complete, and they are still not able to get close to the pump room where the explosion is thought to have originated because the building is not structurally safe.

U.S. Chemical Safety Board Chairman John Bresland said venting a line that contained natural gas inside a building would have been a highly unusual procedure.

"In my mind that would seem to be a risky operation," he offered.

In addition to the three workers killed, 38 employees and three firefighters were injured. Four of those employees suffered critical burns.

Two injured workers filed lawsuits earlier this week against the contracting firm hired by ConAgra to install the heater and a natural gas line to it.

· Click here to read about the lawsuit

There are ten federal investigators working on the review of what happened. Bresland said the work would likely take weeks. So far, they've interviewed more than a hundred eyewitnesses.

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