A commuter train ploughed into a station in New Jersey at the height of Thursday's morning rush hour, killing a woman on the platform and injuring more than 100 people as it brought down part of the roof and scattered debris over the concourse.
Witnesses described terrifying scenes as the front of the train smashed through the track stop at high speed and into the Hoboken terminal, toppling support columns and creating chaos at one of the busiest transit hubs in the New York City area.
"We have no indication that this is anything other than a tragic accident but ... we're going to let the law enforcement professionals pursue the facts," New Jersey Governor Chris Christie said at a news conference in Hoboken alongside New York Governor Andrew Cuomo.
Train #1614 originated in the town of Spring Valley in New York state and was at the end of its hour-long journey when it crashed.
The train's engineer, or driver, was injured and taken to a hospital but later released, officials said, without providing details of his injuries.
Local media identified the engineer as Thomas Gallagher, citing unnamed sources, and said he was cooperating with investigators.
U.S. National Transportation Safety Board vice chairman Bella Dinh-Zarr told a separate news conference in Hoboken that investigators would retrieve the event recorder, which tracks speed, braking and other data, from the rear of the train on Thursday night.
She said the train was operating in a "push-pull configuration" in which locomotive-hauled trains can be driven from either end. The train had an engine that was pushing four cars including the controlling, or cab, car in front, officials said.
"Our investigation will continue here on scene for seven to 10 days," Dinh-Zarr said.
The train was on track five when it hit the Hoboken terminal building at about 08:45 a.m. EDT (1245 GMT).
The New Jersey medical examiner's office identified the victim as Fabiola Bittar de Kroon, 34, of Hoboken. The woman was a former employee in the Brazilian legal department of SAP, the technology company said in a statement. Her LinkedIn page said she was a corporate lawyer who attended Florida International University.
Christie told CNN 114 people were injured. The Chinese Consulate General in New York told Xinhua news service at least one of the injured was a Chinese citizen.
Cuomo said it was obvious the train came into the station too fast, but it was unclear why. The cause could be human error or technical failure, Cuomo said. He added that it was too early to say whether an anti-collision system known as positive train control (PTC) could have prevented the crash. PTC is designed to halt a train if the driver misses a stop signal and advocates cite it for helping to combat human error.
The crash renews focus on the mandatory anti-collision system that has been plagued with lengthy, contentious delays. According to a report by NJ Transit to the Federal Railroad Administration for the first half of 2016, the public transport system does not have PTC in operation on its 326-mile network.
New Jersey Transit ranked second for the most train accident reports nationwide for commuter railroads from January 2007 through June 2016, behind Amtrak.
New Jersey Transit had 271 accidents, or 18 percent of the total, compared to Amtrak’s 44 percent, according to data from the U.S. Federal Railroad Administration Office of Safety Analysis.
Mike Larson, who works as a machinist for NJ Transit, was 30 feet away from the train just before it slammed into the platform. He told The Journal News of Westchester County, New York, that the train's speed appeared to be about 30 mph.
The speed limit in the station is 10 miles (16 km) per hour, the NTSB's Dinh-Zarr told reporters.
The terminal, listed on the New Jersey Registry of Historic Places, was designed in the Beaux Arts style and construction finished in 1907. It lies on the Hudson River's west bank across from New York City. Its station is used by many commuters travelling into Manhattan from New Jersey and New York state.
Hoboken is the last stop on the lines it serves.
A couple of hundred emergency workers spent the morning shuttling in and out of the station, some carrying the injured on stretchers to ambulances outside. Federal investigators later began examining the wreckage.
Linda Albelli, a 62-year-old from Closter, New Jersey, was sitting in one of the train's rear cars and described how she had felt something was wrong a moment before the impact.
"I thought to myself, 'Oh my God, he's not slowing up, and this is where we usually stop,'" Albelli said. "'We're going too fast,' and with that there was this tremendous crash."
As investigators searched for clues to the cause of the accident, some said it could and should have been prevented.
US Senator Richard Blumenthal of Connecticut, a Democrat on a senate committee that includes transportation matters, said the crash was "hauntingly similar" to past tragedies involving insufficient or unsafe practices or equipment. Blumenthal has advocated for the roll out of the anti-collision system.
"This catastrophe was caused by a runaway train – travelling too fast and out of control. There is no excuse," Blumenthal said in a statement. He said there was an urgent need for better safety technology, new equipment and improved training.
The historic green-roofed Hoboken Station is served by NJ Transit commuter trains connecting much of New Jersey with the country's largest city, as well as the Port Authority Trans-Hudson subway-like system known as PATH, a light rail service and ferry service to New York.
In May 2011, a Port Authority of New York and New Jersey train crashed at Hoboken station, injuring more than 30 people. An investigation by the NTSB determined excessive speed was the main cause of the accident.
An NTSB official said the agency would look at similarities between that one and Thursday's crash.
The Hoboken crash was the latest in a string of fatal train crashes in the United States. The worst in recent years involved an Amtrak train that crashed in Philadelphia in May 2015, killing eight people and injuring more than 200.