UPDATE: 5:20 p.m. ET: National Transportation Safety Board investigators say the derailed Amtrak train was going 106 mph when the engineer hit the emergency brakes moments before the crash.
NTSB board member Robert Sumwalt said the emergency brakes slowed the train to 102 mph.
The train was heading into a curve with a maximum allowed speed of 50 mph. The maximum speed before the curve is 70 mph, Sumwalt said.
UPDATE 3:15 p.m. ET: The Naval Academy midshipman killed in Tuesday night's Amtrak train derailment has been identified as 20-year-old Justin Zemser. His parents issued a statement Wednesday afternoon:
Our son was Midshipman Justin Zemser. He was born on March 25th in 1995. He was his high school’s valedictorian and was just finishing his 2nd year as Midshipman at the United States Naval ACademy.
He was a loving son, Nephew and cousin, who was very community minded.
This tragedy has shocked us in the worst way and we wish to spend this time grieving with our close family and friends. At this time we ask for privacy from the media.
UPDATE 2:45 p.m. ET: Philadelphia Mayor Michael Nutter confirmed there are now seven fatalities from Tuesday night's Amtrak passenger train derailment.
Nutter said he could not confirm media reports that the train was traveling at twice the speed limit before the wreck.
Nutter clarified an earlier comment that he made saying the train's conductor was treated for injuries. He was referring to the train's engineer, who actually operates the train. Nutter said the engineer was treated and had spoken with investigators. The Philadelphia Inquirer reported that the engineer declined to give a statement to police, leaving with his attorney instead.
Nutter said the search area has been expanded around the site of the wreck "in case someone was possibly thrown from the train."
UPDATE 1:30 p.m. ET: The Wall Street Journal has reported that the Amtrak passenger train was traveling at 100 mph, twice the speed limit, heading into a sharp curve when it derailed.
UPDATE 12:43 p.m. ET: The body of a seventh victim has been pulled from the wreckage of the derailed Amtrak passenger train, according to the Philadelphia Inquirer.
Investigators and first responders work near the wreckage of Amtrak Northeast Regional Train 188, from Washington to New York, which derailed Tuesday night, May 12, 2015 in north Philadelphia. The body of a seventh victim was pulled from the wreckage Wednesday. Hundreds of other people were injured. (Win McNamee/Getty Images)
UPDATE 12:20 p.m. ET: An Associated Press video software architect is among the six people killed in the Philadelphia Amtrak train derailment.
Jim Gaines, a 48-year-old father of two, had attended meetings in Washington. He was returning home to Plainsboro, New Jersey, when the train derailed Tuesday night. His death was confirmed by his wife, Jacqueline.
Gaines joined the AP in 1998 and was a key factor in nearly all of the news agency's video initiatives, including a service providing live video to hundreds of clients worldwide.
Gaines won AP's "Geek of the Month" award in May 2012 for his "tireless dedication and contagious passion" to technological innovation.
He was part of a team that won the AP Chairman's Prize in 2006 for developing the agency's Online Video Network.
He is also survived by 16-year-old son Oliver and 11-year-old daughter Anushka.
— Associated Press
Investigators and first responders work near the wreckage of an Amtrak passenger train that was carrying more than 200 passengers from Washington, D.C., to New York City when it derailed Tuesday night, May 13, 2015 in Philadelphia. Six people were killed and hundreds injured. (Win McNamee/Getty Images)
UPDATE 11:20 a.m. ET: President Barack Obama in a statement called Tuesday night's Amtrak train derailment "a tragedy that touches us all."
Along with Americans across our country, Michelle and I were shocked and deeply saddened to hear of the derailment aboard Amtrak Train 188. Our thoughts and prayers go out to the families and friends of those we lost last night, and to the many passengers who today begin their long road to recovery. Along the Northeast Corridor, Amtrak is a way of life for many. From Washington, DC and Philadelphia to New York City and Boston, this is a tragedy that touches us all. As we work to determine exactly what happened, I commend the fire, police and medical personnel working tirelessly and professionally to save lives. Philadelphia is known as the city of brotherly love – a city of neighborhoods and neighbors – and that spirit of loving-kindness was reaffirmed last night, as hundreds of first responders and passengers lent a hand to their fellow human beings in need.
UPDATE 11:10 a.m. ET: A U.S. Naval Academy midshipman is among the six people killed in Tuesday night's Amtrak train derailment, WRC-TV reported. The Naval Academy said the midshipman was on leave and on their way home when the derailment occurred.
Rescuers work around derailed carriages of an Amtrak train in Philadelphia, Wednesday, May 13, 2015, after it derailed Tuesday night en route from Washington to New York City. (JEWEL SAMAD/AFP/Getty Images)
UPDATE 10:40 a.m. ET: Philadelphia officials said more than 200 patients have been treated at area hospitals since Tuesday night's Amtrak train derailment.
A search and rescue effort is ongoing.
Philadelphia Mayor Michael Nutter said "we don't have an accurate count" on how many people are still unaccounted for.
Nutter said the train's "black box" has been recovered and is now at Amtrak's operations center in Delaware for analysis.
"There are some things we know, there are many things we do not know at this time," Nutter said. The mayor said there would not be any speculation about what happened until the facts are confirmed.
Nutter said the train's conductor was treated for injuries and was talking with investigators.
Both passengers and their families were directed to call Amtrak at 1-800-523-9101 to confirm they are OK or to check on their loved ones' status.
Nutter said he could not give any details about the six confirmed fatalities.
"Again this is a horrific scene, i just need your patience and understanding," he said.
Rescue crews and investigators inspect the site of an Amtrak train derailment in Philadelphia, May 13, 2015. At least six people were killed and hundreds injured Tuesday night when a passenger train heading from Washington to New York City went off the track in the Port Richmond neighborhood of Philadelphia. (Samuel Corum/Anadolu Agency/Getty Images)
UPDATE 7:30 a.m. ET: A sixth person has died following an Amtrak train derailment in Philadelphia.
Temple University Hospital's Dr. Herbert Cushing says a person died there overnight from a chest injury. That's in addition to the five deaths announced by Mayor Michael Nutter on Tuesday night.
The National Transportation Safety Board expects to have full crews at the scene Wednesday morning to try to determine what happened.
The train was carrying 238 passengers and five crew members as it headed from Washington to New York City along the nation's busiest rail corridor.
Amtrak has modified Northeast Corridor service. Trains will run between Washington and Philadelphia, Harrisburg and Philadelphia, and New York and Boston. There will be no Amtrak service between New York and Philadelphia. New Jersey Transit will honor Amtrak tickets between New York City and Trenton.
— Associated Press
Original story by the Associated Press; curated by Oliver Darcy.
PHILADELPHIA (AP) — An Amtrak train headed to New York City derailed and tipped over in Philadelphia on Tuesday night, mangling the front of it, killing at least five people and injuring several more. Some passengers climbed out of windows to get away.
Mayor Michael Nutter, who confirmed the deaths, said the scene was horrific.
"It is an absolute disastrous mess," he said. "Never seen anything like this in my life."
Firefighters said dozens of people were hospitalized and six were critically injured.
Medics tending to people on stretchers. http://t.co/1W3pF0ycrQ— Vinny Vella (@Vinny Vella)1431483730.0
Train 188, a Northeast Regional, had left Washington, D.C. The front of the train was going into a turn when it started to shake before coming to a sudden stop.
An Associated Press manager, Paul Cheung, was on the train and said he was watching Netflix when "the train started to decelerate, like someone had slammed the brake."
"Then suddenly you could see everything starting to shake," he said. "You could see people's stuff flying over me."
A video posted by Yameen Allworld "Holladay" (@yameenallworld) on
Cheung said another passenger urged him to escape from the back of his car, which he did. He said he saw passengers trying to escape through the windows of cars tipped on their side.
"The front of the train is really mangled," he said. "It's a complete wreck. The whole thing is like a pile of metal."
The cause of the derailment was unknown, but Amtrak said it was investigating. The area where the derailment occurred is known as Frankford Junction and has a big curve.
Police swarming around the crash site, in Port Richmond, a working-class area, told people to get back, away from the train. They pleaded with curious onlookers: "Do NOT go to scene of derailment. Please allow 1st responders room to work."
Roads all around the crash site were blocked off. Waves of firefighters continuing toward the train cars, taking people out.
Several injured people, including one man complaining of neck pain, were rolled away on stretchers. Others wobbled while walking away or were put on city buses. An elderly woman was given oxygen.
Former U.S. Rep. Patrick Murphy was on the train and said he helped people. He tweeted photos of firefighters helping other people in the wreckage.
"Pray for those injured," he said.
Amtrak said the train was carrying 238 passengers and five crew members. It said rail service on the busy Northeast Corridor between New York and Philadelphia was stopped.
The National Transportation Safety Board said it was gathering information about the derailment. It said it was launching an investigative team, which would arrive at site Wednesday morning.
Details on an NTSB media briefing on the #Amtrak accident will be announced in the morning.— NTSB (@NTSB)1431487557.0
Another Amtrak train crashed on Sunday. That train, bound for New Orleans, struck a flatbed truck at a railway crossing in Amite, killing the truck's driver and injuring two people on the train.
In March, at least 55 people were injured when an Amtrak train collided with a tractor-trailer that was stuck on the tracks in North Carolina.
Port Richmond, the site of Tuesday's crash, is one of five neighborhoods in what's known as Philadelphia's River Wards, dense rowhouse neighborhoods located off the Delaware River.
This is a developing news story.