Why Am I Not Relieved By This?

The FBI claims the refinery explosion was not linked to terrorism:

We've found no evidence to support criminal or terrorist activity," Al Tribble, spokesman for the FBI office in Houston, told AFP.

The e-mails were apparently from "two specific Islamic groups", Tribble said. But he said he did not know the names of the groups.

BP said the cause of the blast was still being investigated, but has ruled out terrorism.

It said the explosion occurred when a unit of the refinery that adds octane to gasoline (petrol) was being brought back online after being shut down for routine maintenance.

A year ago the FBI warned Texas oil refineries of a potential terrorism threat in the wake of deadly train blasts in Madrid, which came two-and-a-half years after the September 11 attacks on the United States.

I don't know how one "rules out" terrorism if one doesn't know the cause of the explosion yet.