CHICAGO (AP) – An eight-car Chicago commuter train plowed across a platform and scaled an escalator at an underground station at one of the nation’s busiest airports early Monday, injuring 32 people on board, officials said.

No one suffered life-threatening injuries in the Blue Line derailment at O’Hare International Airport, Chicago Fire Commissioner Jose Santiago said during a morning briefing.

Chicago Transit Authority investigators along with the city fire department and police were reviewing security footage and interviewing the driver and other CTA workers to pin down the cause of the accident around 2:50 a.m. National Transportation Safety Board investigators were expected to arrive later in the day.

“We will be looking at equipment. We will be looking at signals. We’ll be looking at the human factor and any extenuating circumstances,” CTA spokesman Brian Steele said. “But really at this point, it’s far too soon to speculate.”

Transit agency officials said crews were working to remove the train and fix the escalator, which received “significant damage.” Hours after the crash, the front of the first car could still be seen near the top of the escalator.

Christopher Bushell, CTA’s chief infrastructure officer, said it would likely be at least 12 to 24 hours before the station would reopen. He said workers will cut the train apart and remove it in pieces on a flatbed.

The CTA was busing passengers to and from O’Hare to the next station on the line.

The train appeared to have been going too fast as it approached the end-of-line station and didn’t stop at a bumping post – a metal shock absorber at the end of the tracks.

“The train actually climbed over the last stop, jumped up on the sidewalk and then went up the stairs and escalator,” Santiago said.

“Apparently (it) was traveling at a rate of speed that clearly was higher than a normal train would be,” Steele said.

It wasn’t clear how many people were on board at the time of the crash, but that it took place during what is “typically among our lowest ridership time,” Steele said.

The injured were taken to four hospitals and Santiago said most were able to walk away from the wreck unaided.

In September, a CTA Blue Line train slammed into another train at a suburban Chicago station, injuring as many as four dozen commuters.