This story was updated March 24 at 5 p.m. ET.
More than thirty people were injured Monday morning when a train derailed at Chicago's O'Hare International Airport.
"The train actually climbed over the last stop, jumped up on the sidewalk and then went up the stairs and escalators," Chicago Fire Department Commissioner Jose Santiago told NBC Chicago.
None were seriously injured in the incident, which occurred at 2:50 a.m. local time on the Blue Line. Six of the injured were listed in fair condition and 26 in good condition after the accident. A Chicago Transportation Authority spokesperson said it was too early to say what caused the crash, but authorities were investigation and the National Transportation Safety Board had been notified.
A @cta Blue Line train crashes thru end of platform, rides up escalator @ OHare. 32 people hurt, not life-threatening pic.twitter.com/3bfJRrgJzX— WGN TV News (@WGNNews) March 24, 2014
Witness: told @anthonyponceTV 'no-one seriously injured' after @ctablue derailment. Shuttles Rosemont/O'Hare pic.twitter.com/QSC7m6gfwH— Kye Martin (@KyeCommuteNBC) March 24, 2014
“We will be looking at everything -- equipment, signals, the human factor," the spokesperson said. He added, though, that speed may have been a factor.
"It appears as though the train would have been going faster than a train normally birthing at this station would be," he said. "Normally a train pulls in at just a couple miles and hour and pulls into the station. Obviously this train did not stop so speed could be a factor here."
Later on Monday, the president of the Amalgamated Transit Union said the driver may have nodded off moments before the crash, the Chicago Tribune reports. “I can confirm that she was extremely tired,” Robert Kelly said. “Indications are she might have dozed off.”
Blue Line service continues to be suspended btwn Rosemont and O’Hare due to a derailment; bus shuttles are available.— cta (@cta) March 24, 2014