Mass subway exit as Chicago train leaves track

Hundreds of Chicago commuters made emergency exits from the U.S. city’s subway system after a train derailed, causing an underground fire. The fire filled a tunnel with smoke and covered passengers with soot.

At least two are critically injured, and 152 are in hospital.Explosives and anti-terror experts were called to the scene. Police said there was no evidence of foul play and that the fire began when one carriage of an eight-car train left the tracks.