(CNN) Amtrak's president says the company is "profoundly sorry" after a train derailed this week in Washington state and hurtled off an overpass onto a freeway, killing three people.

"We share everyone's sense of urgency to identify exactly what caused this to happen, and we continue to fully cooperate with the investigation being led by the NTSB," Richard Anderson said in a statement.

All the crew members are hospitalized, and the National Transportation Safety Board is setting up interviews with them to get more details on Monday's crash of Amtrak Cascades 501 near DuPont, Washington. The train was on its inaugural journey from Seattle to Portland, Oregon.

So far, there are many questions but few answers. It's unclear why the train was traveling 80 mph in a 30-mph zone, NTSB member Bella Dinh-Zarr said.

Adding to the mystery, positive train control, the technology that can automatically slow down a speeding train, wasn't activated.

"The locomotive was in the process of getting a system of PTC installed, but it was not yet functional," Dinh-Zarr said. Instead, that segment of tracks had centralized traffic control, she said, which can't enforce speed restrictions on a train like PTC.

Victims' families and officials struggled to understand how the tragedy happened.

"There are a thousand unanswered questions about this right now," Washington Gov. Jay Inslee said. "One of the questions is, could that speed control have made a difference? We don't know that for sure at the moment either."

Photos: Amtrak train derails over interstate A train car is lifted away on Tuesday, December 19, the day after an Amtrak passenger train derailed near DuPont, Washington. Several of the train's cars spilled off an overpass and onto Interstate 5. Hide Caption 1 of 14 Photos: Amtrak train derails over interstate Two damaged train cars sit on flatbed trailers after being taken away from the scene on December 19. When it derailed, the train was going 80 mph in a 30 mph zone. Federal investigators said they don't know why yet. Hide Caption 2 of 14 Photos: Amtrak train derails over interstate Men work at the scene of the derailment on December 19. Hide Caption 3 of 14 Photos: Amtrak train derails over interstate Emergency workers respond to the derailment shortly after it happened on Monday, December 18. Hide Caption 4 of 14 Photos: Amtrak train derails over interstate Law enforcement officials work at the scene of the derailment on December 18. The train was making the first trip of a new route that goes from Seattle to Portland, Oregon. Hide Caption 5 of 14 Photos: Amtrak train derails over interstate At least three people were killed and more than 100 were injured, according to DuPont Fire Chief Larry Creekmore. Hide Caption 6 of 14 Photos: Amtrak train derails over interstate Some of the train's wreckage is seen at the crash site on December 18. Hide Caption 7 of 14 Photos: Amtrak train derails over interstate An aerial view of the site on December 18. Hide Caption 8 of 14 Photos: Amtrak train derails over interstate Some motorists were also injured by the fallen train cars. Hide Caption 9 of 14 Photos: Amtrak train derails over interstate The National Transportation Safety Board sent a team to investigate the derailment. Hide Caption 10 of 14 Photos: Amtrak train derails over interstate The train had 86 people aboard, including crew members. Hide Caption 11 of 14 Photos: Amtrak train derails over interstate First responders work at the scene of the crash on December 18. Hide Caption 12 of 14 Photos: Amtrak train derails over interstate All southbound lanes of the interstate were closed due to the derailment. Hide Caption 13 of 14 Photos: Amtrak train derails over interstate The incident took place at 7:40 a.m. near DuPont, which is between Tacoma and Olympia. Hide Caption 14 of 14

Latest developments

• Amtrak's president is apologizing for the train derailment, which also injured 100 others.

• "We are profoundly sorry for those who have lost a loved one, were injured, or are otherwise impacted by this horrible event," Anderson said.

• All three victims have been identified. They are Benjamin Gran, Jim Hamre and Zack Willhoite.

• At least 24 people injured in the crash remain hospitalized, officials said.

• Two people were in the cab in the front locomotive during the crash, the NTSB's Dinh-Zarr said. The engineer was joined by a conductor who was learning the new route, she said. Amtrak's Anderson said such an arrangement is not unusual.

• Data recorders from the front and rear locomotives have been recovered, Dinh-Zarr said. Cameras from the train were damaged and have been sent to Washington, D.C., to see whether video can be retrieved.

• Some lanes of Interstate 5 that have been closed since the derailment reopened Wednesday night, the Washington State Department of Transportation said via Twitter.

• The governor tweeted that Amtrak's Anderson had committed to paying for the impact of the derailment.

"Those costs include all the medical and incidental expenses incurred by those injured and their families, the cleanup and repair of the roadway, and the restoration of passenger rail service," Inslee wrote.

The victims

The injured included Timmy Brodigen, 16, who had planned to spend time with family before Christmas, CNN affiliate KATU reported.

He has had multiple surgeries and procedures after suffering compressed vertebrae and bleeding in the brain.

"Timmy is hooked up to every machine known to man that you can imagine," a cousin, Tab McFadden, told the TV station, adding that his family has set up a GoFundMe page to help with medical costs.

"It just crushes you, it breaks your heart to see this," he said.

On Wednesday, the Pierce County medical examiner's office identified Benjamin Gran, 40, from Auburn, Washington, as one of the three men killed.

The two other victims were Jim Hamre, 61, and Zack Willhoite, 35, the Rail Passengers Association said. Hamre and Willhoite wanted to experience the first trip on the new service route.

The two friends traveled to ride trains together, CNN affiliate KIRO reported. They were also members of All Aboard Washington, a rail advocacy group in their home state.

'We have to assure people's confidence in rail transit'

Investigators will likely examine the track, human performance, operations and mechanics of the train. The track in Washington state had undergone millions of dollars of improvements and weeks of testing.

Two damaged train cars sit on flatbed trailers after being taken from the train crash scene on I-5.

"We have to assure people's confidence in rail transit," Inslee said. "It's very difficult to understand, but rail transit is still the safest method of transit today. But that's not good enough for us. We want zero accidents and zero tragedies of this nature."

The NTSB has recommended the use of PTC for decades. Railroad companies have until the end of 2018 and a possible extension to 2020 to implement the costly system.

Amtrak's Anderson told reporters Tuesday: "It's not clear yet from the NTSB whether PTC would have prevented the accident or not. We really must wait for the NTSB to give us that information."