A Chicago Transit Authority train collided with a standing train at a station in a western suburb of Chicago during Monday morning rush hour, leaving at least 33 people injured, a CTA spokeswoman said.
The collision happened about 7:45 a.m. local time at the ground-level Harlem Station in Forest Park, west of Chicago, spokeswoman Catherine Hosinski said.
Thirty-three people, including the operator of the standing train, were transported to nine hospitals with what appeared to be non-serious injuries, Hosinski said.
The National Transportation Safety Board said it was sending investigators to Chicago in response to the collision. The CTA also is investigating whether there was an operator or anyone else on the moving train, which had no customers.
Forest Park Mayor Anthony Calderone gave a slightly higher number of injured, saying 48 people had been transferred to 10 hospitals, adding that none of their injuries was life-threatening.
"Most of the people were complaining of either neck pain or back pain," Calderone told the CLTV news station.
Service resumed across the affected line by midday, but trains were skipping the station where the collision occurred, the CTA said.
Robert Kelly, president of the union that represents train operators, said the moving train was apparently empty and safety mechanisms should have stopped it automatically before it entered the station.
"Right now it is starting to look like a mechanical malfunction," Kelly said.
Calderone said Forest Park police were treating the station as a crime scene as a precaution to preserve evidence, though they were not saying any crime had occurred.
© 2015 Thomson/Reuters. All rights reserved.