Crescent City, Fla. ? The engineer of the Amtrak train that crashed near this hamlet told investigators he threw on the emergency brakes just before the deadly derailment because he saw misaligned tracks ahead, the NTSB said Friday.

More than half of the Auto Train’s 40 cars skidded off the tracks Thursday. Four people were killed and more than 150 injured.

	Less than 24 hours after Thursday’s Auto Train crash, a Boca Raton, Fla.-based law firm filed a lawsuit in federal court in Jacksonville, Fla., seeking class-action status on behalf of the train’s passengers.

George Black of the National Transportation Safety Board said investigators have not yet determined what caused the train to hurtle off the tracks. He said investigators were still trying to confirm whether the track was out of alignment.

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 Black 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.

Amtrak spokeswoman Cheryl Jackson said sabotage was not suspected.

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 was not released.

The train, which carries both passengers and cars and is a favorite among tourists traveling between Washington and Orlando’s theme parks, was going 56 mph in a 60 mph zone when the accident happened, Black said.

The death toll was reported at six Thursday but was revised Friday by investigators and medical officials. In all, 166 passengers were taken to hospitals. Twelve remained hospitalized, including a 73-year-old woman in critical condition.

The names of the dead were not immediately released.

The Auto Train was bound for Washington with 418 passengers and 34 crew members.

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 derailed.