BILOXI, Miss. — The National Transportation Safety Board (NTSB) determined the probable cause of 2017’s fatal bus/train collision, which killed four people, was a failure by the City of Biloxi and CSX Transportation to properly communicate that vehicles get stuck on the tracks, WLOX reports.

The two entities were also reprimanded for not taking action to improve the safety of the grade crossing on Main Street, where the collision happened. NTSB announced maintenance that raised the crossing in 2014 resulted in nearly 20 incidents of vehicles getting stuck on the crossing, including the March 2017 collision, where an Echo Transportation motorcoach was stuck on the tracks when it was struck by a CSX freight train.

There were 15 findings from the NTSB investigation, including better communication and more proactive measures from every agency involved. Eleven safety recommendations came from the accident investigation, including more warning signs at these high-grade crossings, pre-trip safety briefings for bus trips, and warnings to railroad conductors about the numerous steep grade crossings in Biloxi. For the full story, click here.