Three Held in Attempted Bombing of Chemical Tanks : Crime: FBI investigators believe that an insurance plot, not terrorism, was the motive.

The FBI said Saturday it had arrested three men in connection with a possible attempt to blow up two huge chemical storage tanks near a U.S. Navy base at Norfolk, Va. Officials cited extortion rather than terrorism as the apparent motive.

The discovery last Monday of six pipe bombs attached to the storage tanks triggered an immediate federal investigation because of the possibility that the incident marked the beginning of a terrorism campaign encouraged by Iraqi President Saddam Hussein.

In a statement Saturday, the FBI said the three suspects had been charged with conspiring to use the explosives to commit mail and wire fraud.

They were identified as Joseph Openshaw, 26, of St. Johns, Ariz.; Cecil Ross, 31, of Glendale, Ariz., and Charles Gresham, 57, of Ellicott City, Md. Openshaw and Ross were arrested Friday in Arizona, and Gresham was taken into custody in Ellicott City on Saturday morning.

The FBI statement said the three had plotted to collect on an insurance policy covering chemicals stored at the facility, located some five miles from Norfolk Naval Base, the world’s largest Navy base and home port to 35,000 American sailors and carrier-based pilots now in the Persian Gulf. The chemicals belonged to Gresham, the FBI said.

Discovery of the bombs, taped to a pair of million-gallon tanks, one containing highly flammable methanol and another holding caustic sodium sulfide, triggered an evacuation of residents and businesses within a one-mile radius and aroused immediate suspicion of war-related terrorism.

Virginia state police removed the devices and disarmed them without incident.

Although proximity to the huge naval base raised the issue of possible terrorism, investigators were skeptical that the incident was linked to the Persian Gulf conflict. They noted that pipe bombs were used instead of the plastic explosives commonly associated with professional terrorists in the Middle East.

FBI Director William S. Sessions, who announced the arrests, said the FBI will continue to “vigorously and relentlessly pursue all criminal acts, particularly when committed by those who might try to take advantage of an environment of heightened concern because of the Gulf War.”

In the wake of terrorism threats by Iraq’s Hussein, security at the chemical storage facility had been tightened since the outbreak of the war. The bombs were discovered by an employee during a routine check.

It was not clear why the devices had not exploded. If they had, authorities said, they probably would not have caused a catastrophic rupture of the tanks, but a leak could have triggered a huge fire.

The facility, with 15 storage tanks, has no connection with the military and had not been considered a high-risk terrorist target.