Workers with jackhammers tried to pound through the deck of the collapsed Hatchie River bridge this morning looking for the body of an eighth person feared to have been trapped beneath the structure.

A tractor-trailer and three cars were known to have gone into the water when a 60-foot section of the half-century-old bridge collapsed Saturday night, killing at least seven people.Authorities were looking for a fourth car because a local man was reported missing and "he should have been on this road about that time," said Jacky Carter, an investigator with the Tennessee Emergency Management Agency. Divers also joined in the search but were hampered by bad weather, officials said.

Months of flooding on the Hatchie may have eroded the foundation of a bridge pier, causing the U.S. 51 span to fail, said the state highway commissioner.

Investigators said they believe one segment collapsed first, plunging the cars into the water. Then, Carter said, "when the tractor-trailer went off, he knocked a pillar down and then the rest of the slab fell in."

Gov. Ned McWherter said Monday the bridge had been visually inspected a few weeks ago for cracks.

"There were none visible," the governor said during an appearance in Smyrna. "If we had had any indication of any danger at all, we would have closed the bridge."

A 1987 inspection found no abnormalities, but the collapse probably will lead the state to review its procedures, said Bill Moore, a state transportation department inspector.

A team of nine divers re-entered the flooded river Monday morning and planned to search as long as the weather would permit, though they were hampered by an inch of rain overnight and bursts of quarter-sized hail Monday.

"It was just terrible," Cecil Whaley, operations officer for the emergency management agency, said Monday morning. "We are facing a 60 to 80 percent chance of the same type of weather today."

The collapse of the two-lane, northbound bridge occurred Saturday night about 45 miles north of Memphis. A companion two-lane southbound bridge was unaffected, although it remained closed following the cave-in, the Tennessee Highway Patrol said.

It was not known how many people were riding on the bridge when it crumbled, authorities said.