NEW : The train that caused the accident had been parked in a service yard . NEW : Authorities are investigating whether someone climbed on board . NEW : 48 people were injured ; 48 taken to hospitals , WLS affiliate CNN reported . The crash affected Illinois 's early 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 : 48 people were injured ; 33 taken to hospitals , CNN affiliate WLS reported . The crash affected Chicago 's Monday morning commute .