A video that appears to capture the dramatic derailment of a subway train at Chicago’s O’Hare International Airport has been posted to YouTube.
The Chicago "L" transit system's Blue Line train derailed Monday at the station that is located at O'Hare, which is the second busiest airport in the U.S.
The video shows apparent security footage of the train entering the airport station at a high speed and crashing into an escalator that leads up to the airport.
The National Transportation Safety Board (NTSB) is investigating the accident. The agency has suggested that the driver of the train possibly fell asleep at the controls, leading to the accident.
Investigators have said the Chicago train derailment could have been much more deadly if it had occurred later in the day.
In addition to O’Hare being the second busiest airport in the U.S., the Chicago subway is the third busiest public transit system in the U.S. The system has an average of weekday ridership of 734,900, according to the American Public Transportation Association (APTA).
The Chicago subway’s ridership is only surpassed by the New York City subway and Washington, D.C.'s Metrorail.
Neither the NTSB or the Chicago Transit Authority has confirmed the authenticity of the accident footage yet.