Chicago : The train that caused the accident had been parked in a rail yard . Chicago : Authorities are investigating whether someone was on board . NEW : 48 people were injured ; 33 taken to hospitals , CNN affiliate Chicago reported . It was not immediately clear how many passengers were aboard the train . The crash disrupted Chicago 's Monday morning commute .
Chicago : The train that caused the accident had been parked in a rail yard . Chicago : Authorities are investigating whether someone was on board . NEW : 48 people were injured ; 33 taken to hospitals , CNN affiliate Chicago reported . The crash disrupted Chicago 's Monday morning commute .