DEVELOPING: Amtrak train derails onto Interstate 5 in Washington state cbsn.ws/2j9xWKB
MORE: First responders are treating the derailment as a mass casualty incident, CBS News affiliate KIRO-TV reports cbsn.ws/2jc6LyW
“There are emergency crews everywhere, helping all of the injured,” passenger on derailed train says cbsn.ws/2oDNSu5
SPECIAL REPORT: Emergency crews are responding to a major train derailment in Washington as a mass-casualty incident cbsn.ws/2oDNSu5
Amtrak train # 501 was part of a new high-speed service that just launched today, CBS affiliate @KIRO7Seattle reports cbsn.ws/2oDNSu5
“Those are new cars, but the real question is, are they new tracks?” CBS News Travel Editor @PeterSGreenberg says. “The NTSB will be investigating almost immediately." cbsn.ws/2oDNSu5
“We were reaching sort of a bend in the tracks, and all of a sudden, we were slammed into the seats in front of us. And then the car careened down an embankment,” passenger Chris Karnes, says of Amtrak derailment cbsn.ws/2oDNSu5
"There were multiple people injured. There’s military police, firefighters, medical aid of all sorts. They're on the scene right now,” passenger Chris Karnes, says of Amtrak derailment in Washington state cbsn.ws/2oDNSu5
“There are several other cars that seem to have piled up and been torn apart on top of the rail overpass. And then there's at least one car that seems to be hanging off of the overpass at the moment” passenger Chris Karnes, says of Amtrak derailment cbsn.ws/2oDNSu5
.@NorahODonnell: Chris, what types of injuries did you see?
Chris Karnes, train passenger: Cuts, people bleeding, I did see -- I did see one person who was laying on the ground and was not moving cbsn.ws/2oDNSu5
Chris Karnes, train passenger: Cuts, people bleeding, I did see -- I did see one person who was laying on the ground and was not moving cbsn.ws/2oDNSu5
“Typically, this type of Amtrak train would have 13 cars in it and could have up to 250 passengers,” @NorahODonnell reports cbsn.ws/2oDNSu5
The Amtrak train that derailed is partially hanging off an overpass on to Interstate 5, which stretches from Mexico through Washington state cbsn.ws/2oDNSu5
“Amtrak only owns relatively small portion of the 62,000 miles of track in the United States. So they'll be looking and they'll be working with the railroad that actually owns that track and they will become a party to this investigation,” Former NTSB Chairman Mark Rosenker says
.@NorahODonnell: It reached 78.5 mph traveling between Seattle and Tukwila. After stopping in Tacoma, it sped up to 81 mph before derailment.
Rosenker: It may well have been doing its maximum speed. cbsn.ws/2oDNSu5
Rosenker: It may well have been doing its maximum speed. cbsn.ws/2oDNSu5
“The locomotive will actually have what they call an event recorder. Very similar to a black box in an aircraft. They will be able to get a lot of data from that particular box when it's finally downloaded,” Rosenker says cbsn.ws/2oDNSu5
NEW: Photos shared by Washington state trooper shows some Amtrak train cars on highway, other dangling from bridge (courtesy Trooper Brooke Bova @wspd1pio) cbsn.ws/2jcYyKM 
“We've just heard from the Pierce County Sheriff's Spokesman Ed Troyer that there are fatalities” in the Amtrak derailment, @NorahODonnell reports cbsn.ws/2oDNSu5
“Those are fairly new train cars, they have been engineered to be crash resistant,” @KrisVanCleave reports of Amtrak #501 that derailed in Washington state this morning cbsn.ws/2oDNSu5
70 people were on this Amtrak train when it derailed, CBS News Seattle affiliate @KIRO7Seattle reports cbsn.ws/2oDNSu5
Pierce County officials say “several cars on I-5 were struck by the derailed Amtrak train cars. Multiple motorists injured on the roadway. They say no fatalities reported amongst the motorists yet,” @krisvancleave reports cbsn.ws/2oDNSu5
NEW: Several cars are stuck on an Interstate in Washington state after an Amtrak train derailed Monday morning. "Multiple motorists injured on roadway, no fatalities of motorists reported," @PierceSheriff says cbsn.ws/2oDNSu5
"Once they've gotten a head count, that's when we're going to start to get some really solid information. Right now, we are in that stage of breaking news, where numbers are going to change a little bit here and there," @krisvancleave says on train derailment
“This was a new high-speed route. The expectation was that it would shave about 10 minutes off of the train passengers' commute," @AMGreenCBS reports. "The derailment occurred in an area where there is a slight curve." cbsn.ws/2oDNSu5
PHOTOS: Images from the scene of Washington interstate where Amtrak train has derailed. A train car is seen dangling from overpass and some train parts are scattered on highway (Courtesy @PierceSheriff) cbsn.ws/2oDNSu5
"[I-5] is a major transportation corridor for commuters, as well as freight. And it is very close to Joint Base Lewis-McChord which is one of the largest military bases on the west coast," WSDOT's Claudia Bingham-Baker says of highway where train derailed
“These tracks had been used previously for freight traffic. And they had been rebuilt to carry this 79 mph new Amtrak cascades route,” WSDOT's Bingham-Baker says cbsn.ws/2oDNSu5
“At 7:40 this morning the train derailed...There were some fatalities and there were a lot of injuries. And some people were able to get off the train,” official says of Amtrak derailment in Washington state cbsn.ws/2oDNSu5
