Four passengers who died when their Amtrak Auto Train derailed in northern Florida were all vacationers and snowbirds returning to the North, investigators said Saturday.

The dead were identified as Frank Alfredo, 68, of Waccabuc, N.Y.; Joan DiStefano, 65, of Staten Island, N.Y.; and Joseph and Marjorie Wright, of Toronto.

More than half of the Auto Train's 40 cars left the tracks in the Thursday accident, which left more than 150 people injured.

Investigators trying to determine the cause of the derailment were looking into the possibility that the track was out of alignment, the National Transportation Safety Board said.

About two dozen workers dressed in hard hats and reflective vests resumed their work Saturday amid the rumble of heavy equipment to clear the remaining cars from the track. A steady stream of local residents visited the site.

Judy Poppen, of Satsuma, a community 15 miles north of the crash site, said the lack of train activity has left a strange silence in their town.

"We're used to having a train go by," Poppen said. "Now it's quiet."

The engineer of the Auto Train said he pulled the train's emergency brakes just before the derailment when he saw misaligned tracks ahead, investigators said.

The tracks had been visually inspected eight hours before the crash and had been in good condition, according to CSX, the freight railroad that owns the track. A National Railroad Administration inspection last week and two other inspections in the past six months turned up no problems.

It is not uncommon for rails to expand in the Florida heat, but George Black of the NTSB said the temperature – 81 degrees – did not appear to be a factor. Misalignments can also be caused by damage done by a previous train.

Black said four other trains had passed over the area just before the wreck, apparently without trouble. He said investigators examined two of those trains for signs of damage from bad track and found no problems.

The engineer, who was not hurt, was tested for drugs, a routine step after an accident. The results were not immediately disclosed. The engineer's name and background were not released.

Amtrak spokeswoman Cheryl Jackson said sabotage was not suspected.

Twelve people remained hospitalized from the accident, including a 73-year-old woman in critical condition.

The Auto Train was bound for Washington with 418 passengers and 34 crew members, as well as 200 automobiles stacked in 23 specially designed cars.

The accident happened about an hour into the trip. The two engines and first two cars stayed on the track, but 14 of the 16 passenger cars and seven others derailed in the remote, heavily wooded area 60 miles north of Orlando.

The derailment was Amtrak's deadliest crash since March 15, 1999, when a train collided with a truck and derailed near Bourbonnais, Ill., killing 13 people and injuring more than 100.

The last Auto Train accident happened in 1998, when a train hit an empty car at a crossing in the Virginia town of Jarratt. There were no injuries.

The Auto Train service carried 234,000 passengers in 2000, according to Amtrak, making it one of the most popular and successful routes of the nation's passenger rail line.

The Amtrak Reform Council, a body created by Congress, reported this year that Amtrak made money in 2000 only on the Auto Train and on rail lines in the Northeast.

The Auto Train, a favorite among tourists traveling between the Northeast and Orlando's theme parks, was going 56 mph in a 60 mph zone when it derailed, Black said.