Authorities say they are unaware of any terrorist links to six pipe bombs safely removed from two chemical tanks located not far from the world's largest naval base.

The bombs, pieced together to form two devices with each attached to a separate storage tank, were safely removed Monday in a tense, all-day operation that included the evacuation of a mile-square area.Authorities said no one claimed responsibility for the bombs or called with a threat to the storage site. "We have had nothing to indicate this would happen," said Norfolk Police Department spokesman Bob Haynes.

Meanwhile, a bomb threat Tuesday forced the closing of the tunnel linking Norfolk and Portsmouth. Haynes said traffic was routed away from the Downtown Tunnel, a major commuter artery, and authorities were searching the half-mile tunnel for anything suspicious.

And in the northwestern part of the state, a small bomb exploded Tuesday in a car parked in an apartment complex near Eastern Mennonite College in Harrisonburg, 210 miles from Norfolk. One man was treated for shrapnel injuries. Fire Chief Larry Shifflett said there was no evidence that the explosion was linked to terrorism.

The pipe bombs found Monday were at Allied Terminals Inc., a private tank farm on the Elizabeth River. The company is about 10 miles from the Norfolk Naval Base, home port to 35,000 sailors, more than one-third of the U.S. Navy's contingent in Operation Desert Storm.

It is also five miles from the Navy's Craney Island fuel depot.

Haynes said the tank farm has private security but is not considered a high-risk site for terrorism because it has no military role.

Security at the base had been tightened in the wake of Iraqi threats to commit terrorism following the outbreak of the war in the Persian Gulf.

The FBI is leading the investigation "because of a potential for a terrorism nexus," FBI spokesman Bill Carter said in Washington. But Carter stressed that the FBI had not received any word from terrorist groups claiming responsibility for planting the bombs.