In the middle of rush hour on Monday morning, an Amtrak train derailed on a highway overpass south of Seattle, leaving at least three people dead and 10 others seriously injured.
The train was making its maiden run on a new route between Tacoma and Olympia.
Train 501 had been travelling 80 km/h over the speed limit before the crash occurred, the The National Transportation Safety Board said.
WATCH: Were concerns raised about the tracks prior to deadly Amtrak derailment?
Thirteen of the train’s 14 cars jumped the tracks, with several spilling out onto the Interstate 5 Highway. Five vehicles and two trucks were involved in the accident.
The National Transportation Safety Board sent a team of investigators to the site to try to determine the cause of the accident.
The following is a list of what we know and don’t know about the accident:
What we know:
At least three people were killed in the accident. All were passengers aboard the train.
There were 85 people aboard the train when it derailed: 80 passengers as well as five crew members.
Seventy-two passengers were evaluated for injury, Washington State Police Capt. Dan Hall said Monday. Ten of the passengers were said to be in serious condition while 13 others were left with moderate or minor injuries.
Thirteen of the train’s 14 cars jumped the tracks near the town of DuPont, Washington State Patrol spokeswoman Brooke Bova said.
Five vehicles and two trucks were involved in the accident. Some motorists were injured but none have died.
One of the train cars is still hanging from the overpass near Dupont, which is southwest of Seattle. Another train car has fallen to Interstate 5 (I-5) below.
The speed drops from 79 mph (127 kph) to 30 mph (48 kph) for passenger trains just before the tracks curve to cross Interstate 5, which is where the train went off the tracks.
WATCH: NTSB investigators combing over every piece of evidence in Washington derailment
The National Transportation Safety Board said that information from the event data recorder in the rear locomotive showed the train was traveling at 80 mph in a 30 mph zone when it derailed.
The train was making the inaugural run on the new route as part of a $180.7-million project designed to speed up service by removing passenger trains from a route along Puget Sound that’s bogged down by curves, single-track tunnels and freight traffic.
The mayor of Lakewood, Wash., a city along the new route, predicted a deadly crash – but one involving a fast-moving train hitting a car or pedestrian at a grade-crossing, not a train tumbling off an overpass.
This was Amtrak’s 10th derailment in the last seven years including one in Washington state earlier in 2017. A train carrying 250 passengers derailed a few miles north of Monday’s accident in early July although no one suffered serious injuries.
The new Siemens Charger locomotives were equipped with “positive train control” safety systems, designed to automatically stop the train in dangerous situations and mandated for trains around the country. But the technology was only expected to be used next year when it is activated on the entire rail corridor, according to the Washington State Department of Transportation.
The NTSB took over the investigation on Monday night from Washington State Police and the FBI.
What we don’t know
While there have been three deaths so far, an official cautioned that number could rise as over 100 people were taken to nearby hospitals with at least a dozen in serious or critical condition.
WATCH: Aerial view of Amtrak train derailment shows devastation of accident
The cause of the crash has yet to be determined. The National Transportation Safety Board has sent a team to investigate Monday’s crash.
Further, it is unclear exactly how fast the train was going as it approached the bridge. The speed at that point drops dramatically.
*With files from Global News, Reuters and Associated Press