Yesterday, an eight-car commuter train derailed in Chicago's O'Hare airport, crossing a platform and charging up an escalator before coming to a standstill. The accident injured 32 passengers, thankfully, none of them too seriously. Now, what appears to be security camera footage from above the platform shows what the derailment looked like from within the airport.

The unverified video shows two men, apparently a traveller and security officer, casually chatting before bolting away as a train shoots up the escalator. 

According to NBC, it's not entirely clear where the video came from: 

The video, which was deleted just hours after being posted Tuesday night and was re-posted Wednesday morning, shows a train coming into the Chicago station and crashing into escalators. Wednesday's video was posted by user SuccessHab on YouTube. While the footage is the same, it is not clear if it was posted by the same user or where the footage came from.

Investigators suspect that the conductor fell asleep at the helm of the train, and are looking into whether there was also a mechanical failure. The Associated Press reports

National Transportation Safety Board investigator Ted Turpin said a preliminary review showed the train was traveling at the correct speed of 25 mph as it entered the station. Investigators said they have not yet determined whether the operator ever applied the in-cab brake. Turpin, who is leading the investigation, said an automatic emergency braking system located on the tracks was activated but failed to stop the train as it burst onto the platform.

As the investigations continue, lawsuits against the Chicago Transit Authority have already started to pour in, as injured passengers claim damages from the event.