PHOTOS: CTA Blue Line train derailment
The operator of the train told witnesses at the O'Hare station she "nodded off" at the controls.
"There are indications she dozed off, yes," CTA Union President Bob Kelly said. Kelly said the train operator had 17 hours between shifts, but "she had worked a lot of hours in the past week."
The union is investigating whether fatigue played a role in the crash.
"She assured me that there is no problem with her passing the drug and alcohol, that was not a factor in this. She said she was extremely tired," Kelly said.
NTSB leads investigation
NTSB officials are leading the investigation, and on Tuesday plan to interview the train's operator, who was treated and released from a local hospital. A team of six will be sent to Chicago to look at signal, operational and mechanical issues.
The operator reported to work at 8:40 p.m. Sunday. The 200-ton, eight-car train derailed at about 2:50 a.m. Monday. Blue Line run 141 hit with such speed and force that the lead car lifted at least three feet to the platform level while ripping out a bumping post, sheering off the front wheel carriage and flying almost to the top of the O'Hare station escalator.
"All the lights went out on the train. Lots of screaming. I knew something wasn't right," Dion Stokes, passenger, said.
A police officer and traveler saw the train coming and darted out of the way seconds before impact.
"I saw those pictures, and, oh my God, it was pretty serious. Rush hour. Could have been a lot worse. So yeah, I think we are pretty lucky," Robert Armenta said.
Thirty-two people on the train were transported to Lutheran General, Our Lady of Resurrection and Swedish Covenant hospitals.
"I was thrown from my seat and I hit the other seat opposite from me. Twisted my leg real bad," Stokes said.
None of the injuries is life-threatening, officials said. Twenty-six people were taken to local hospitals for bumps, bruises and other minor injuries. Six people had more serious injuries.
"We received seven patients, total, of people who were thrown around the train. The injuries were not significant. We had several patients who had neck discomfort, knee injury, a little bit of head problems," Dr. Douglas Propp, Advocate Lutheran General Hospital, said.
"Almost all of them have been released," Tim DePaepe, signal specialist at NTSB, said.
About 50 people were onboard the train, which some witnesses said was going 20 mph instead of the usual 5 mph. CTA officials said the train passed by at least three trip arms -- including a bumping post two car lengths from the track's end-- which are designed to slow trains down and prevent such accidents.
Some witnesses at the CTA Blue Line station said the train did not appear to slow down at all, while passengers said they felt the brakes being applied at the last minute. Officials will look into why.
"The signal data, will give us information where we can extrapolate speed," DePaepe said.
Officials will look at security video from the station of the train coming in, as well as from the train's front-end camera.
"We will take possession of it and we will send it to Washington, D.C. for examination by our video recorder specialists," DePaepe said.
Shuttle buses running Rosemont to O'Hare on CTA Blue Line
Officials will dismantle the train to remove it from the O'Hare stop, at which point they will have an idea of whether there was any structural damage done to the station. The removal could take 24 hours or longer.
"We're sensitive to the service needs of the CTA but we have to do our documentation first, at least 24 hours I would think," DePaepe said.
The CTA's Blue Line is "roughly on schedule" from Forest Park to Rosemont, CTA President Forrest Claypool said.
"We are running shuttle buses from O'Hare to Rosemont, Rosemont to O'Hare roughly every 5 to 10 minutes," Claypool said.
"We will be looking at equipment. We will be looking at signals. We'll be looking at the human factor and any extenuating circumstances," Steele said. "But really at this point, it's far too soon to speculate."