OMAHA, Neb.>> Federal investigators announced on Tuesday a special investigation into rail operator Norfolk Southern following a fiery derailment on the Ohio-Pennsylvania border in February and several other accidents, including the death of a train conductor just hours earlier Tuesday.

The National Transportation Safety Board said it will begin a broad look at the railroad’s safety culture, saying it has sent investigation teams to look into five significant accidents involving Norfolk Southern since December 2021.

The agency also said it was urging the company to take immediate action to review and assess its safety practices. Norfolk Southern didn’t respond to a request for comment. It announced plans Monday to improve the use of detectors placed along railroad tracks to spot overheating bearings and other problems in response to the derailment in Ohio last month.

— The Associated Press