The derailment happened around 7 p.m. Wednesday. At around 2 a.m., the CTA said trains were running again.
CTA officials said the train was arriving at O'Hare when it derailed between the Rosemont and O'Hare stops. Pictures of the car that derailed show several wheels knocked off the track.
Power was cut from that section of the line so Chicago fire crews could assist passengers in evacuating the derailed train. Fire officials said a 39-year-old woman was taken to Resurrection Hospital with a back injury in stable condition. No other injuries have been reported.
Raw video of Blue Line train evacuation after derailment
As many as 73 people were on board at the time of the derailment. Passengers said they had to walk along a plank inside the tunnel to get to the platform, where they then had to climb onto a shuttle bus to be taken to the Rosemont station.
"The train hit so hard the door shattered and we had to exit the train and walk through from the middle of the terminal to O'Hare," said passenger Kianna Thomas. "Everyone had to move to the back of the train and exit off of the side."
"It took us about eight minutes to walk from the train in single file along this narrow walkway back to the station and there we were," said passenger Glyn Garside.
CTA provided stranded passengers a shuttle bus to and from Rosemont as crews worked for hours to get service back up and running.