National Transportation Safety Board (NTSB) officials hoped interviews with all crew members would shed light on why Train 501 on Amtrak’s Cascades line was going more than twice the speed limit around a curved stretch of track when it derailed on Monday.

The accident occurred during the train’s inaugural run on a new, slightly quicker route between Olympia and Tacoma, with 86 people aboard, 80 of them passengers, Amtrak said.

NTSB officials said they planned to interview all the crew members in the next two days, once they sufficiently recover from injuries suffered in the wreck, including the conductor-in-training who was with the engineer at the time.

Safety board member T. Bella Dinh-Zarr told reporters that NTSB investigators would seek to determine, among other factors routinely examined, whether the engineer was distracted while driving the ill-fated train.

“Distraction is one of our most-wanted-list priorities at the NTSB,” she said.

She also said investigators had determined that the train’s emergency brakes were automatically activated while the derailment was occurring, rather than engaged manually by the engineer.

In addition, she confirmed that a safety system known as positive train control (PTC), which automatically slows trains if they go too fast, was not installed on the rail line. She said Congress had extended a mandatory deadline for having the PTC system installed on all passenger railways to 2018.

None of the crew has been identified. All were hospitalized, Dinh-Zarr said.

Three people aboard the train were killed when all 12 carriages and one of the train’s two locomotives tumbled off the rails onto Interstate 5 near the town of DuPont, about 50 miles south of Seattle, officials said. Another 100 people were taken to hospitals, 10 with serious injuries.

Some motorists were among the injured, though nobody on the highway died.

Recorded data recovered from the rear locomotive showed the train was going 80 miles (129 km) per hour on a bend in the track where the speed limit was 30 mph (48 kph), NTSB officials said on Monday night. The board said it was investigating whether other circumstances besides speed were involved, such as track conditions, signals, mechanical issues and human factors.

Speaking at an afternoon news conference on Tuesday, Dinh-Zarr said that a conductor “who was getting experience and familiarizing himself with the territory” was present in the locomotive cab with the engineer. NTSB spokesman Peter Knudson described that second Amtrak employee as a “conductor-in-training.”

Dinh-Zarr said it was not unusual for conductors who are learning a new train route to ride in the cab with the engineer. She said another conductor was posted in the passenger section of the train at the time.

The derailment placed Amtrak, the country’s main passenger rail service, under renewed scrutiny following a series of fatal incidents.

Seeking to reopen highway

Meanwhile, workers lifted mangled train cars onto flatbed trucks from the wreckage site, using two towering cranes in wet, windy weather as they sought to reopen the southbound lanes of Interstate 5, a major West Coast highway stretching from the Canadian border to Mexico.

They expected to remove five of the cars and the locomotive by Tuesday afternoon and take them to a nearby U.S. military base for further examination, officials said.

The locomotive alone weighs more than 270,000 pounds (120 tonnes) and will require an extra-large truck to move, Dan Hall, the regional commander for the Washington State Patrol, said at a news conference.

The southbound stretch of Interstate 5 will remain closed for several days, the Washington State Department of Transportation said.

At least two of the three people who died in the derailment were transit enthusiasts who wanted to see the maiden run of a new route for the train line, said Abe Zumwalt, director of policy research for the Rail Passengers Association.

Jim Hamre and Zack Willhoite were members of the association, the Washington, D.C.-based organization said in a statement identifying the two men as victims of the wreck. Willhoite worked for a local transportation agency, Pierce Transit, as a customer service support specialist.

“They were best friends and they took all kinds of trips together, and given that yesterday was an inaugural run on a service that both had advocated for tirelessly, it made sense that they were on board,” Zumwalt said in a phone interview.