U.S. railroads were warned by an industry trade group on Thursday to take certain cars out of service following a Norfolk Southern derailment in Ohio last week. 

The rail operator discovered loose wheels on a car involved in the incident – though it is not clear that the loose wheels caused the derailment near Springfield and the National Transportation Safety Board has just begun investigating that crash. The railroad has said loose wheels on the car could cause a derailment. 

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In a statement, Norfolk Southern said that it acted swiftly to notify accident investigators and the industry after discovering "additional cases of unusual wheel movement."

The Association of American Railroads said that all of the steel coil cars with those new wheel sets should be inspected and have the parts replaced. 

Railroads nationwide initially identified 675 cars affected by the advisory and pulled them off the tracks, Association of American Railroads spokeswoman Jessica Kahanek told The Associated Press.

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The trade group also announced additional safety measures, including the installation of approximately 1,000 new hot bearing detectors and a commitment to stop trains and inspect bearings whenever the temperature reading exceeds 170 degrees above ambient temperature. 

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Furthermore, the association said it would train thousands of first responders on accident mitigation and provide the AskRail app to every first responder. The app provides real-time information about the contents of every car in a train and the safe handling of those contents in the event of an accident.

The Associated Press contributed to this report.