Texas city, Texas, March 25, SPA -- FBI agents have ruled outterrorism, but U.S. federal regulators estimate it willtake them months to determine what caused an oil refineryexplosion that killed 15 and injured more than 100. Investigators from two agencies, the Occupational Safetyand Health Administration and the U.S. Chemical SafetyBoard, arrived Thursday at the 1,200-acre BP plant to startsorting through the debris. Also Thursday, an FBI spokesman in Houston dismissed astatement posted on an Islamic Web site claimingresponsibility for the blast. He said there was noindication of foul play.--SPA1355 Local Time 1055 GMT www.spa.gov.sa/249694