The bodies of two people trapped in a car under giant mounds of coal, which spilled from a derailed train near Chicago, have been unearthed and removed from the scene, authorities said.

Wayne Globerger, the fire chief of Glenview, Illinois - the Chicago suburb where the accident occurred - declined to identify either victim.

Globerger told reporters that crews were searching the site north of Chicago for any other vehicles that may have been buried.

31 of 138 cars of a Union Pacific train derailed on an 86-foot-long (26-meter) bridge, spilling large amounts of coal, railroad spokesman Tom Lange said. The derailed cars piled up on the bridge, putting more weight on the structure than if the train had kept moving, and likely caused the bridge to collapse, Lange said.

The derailment may have been caused by steel rails expanding in extremely hot weather.

Initially, no injuries were reported. But authorities cleaning up the debris discovered a car bumper, and then the vehicle with the two victims inside. (Reuters)