NEW : The train that caused the accident had been parked in a service yard . Investigators are not characterizing the incident as a runaway train at this point , Steele said . NEW : Authorities are investigating whether someone climbed on board . NEW : A man who was injured is being treated at an area hospital for minor injuries The crash affected Chicago 's Monday morning commute .
NEW : The train that caused the accident had been parked in a service yard . NEW : Authorities are investigating whether someone climbed on board . NEW : A man who was injured is being treated at an area hospital for minor injuries The crash affected Chicago 's Monday morning commute .