EAST PALESTINE, Ohio >> The crew operating a freight train that derailed in East Palestine, Ohio, did not receive a critical warning about an overheated axle until just before dozens of cars went off the tracks, federal safety investigators said in a report Thursday as U.S. Transportation Secretary Pete Buttigieg made his first visit to the crash site.

An engineer slowed and stopped the train after getting a “critical audible alarm message,” according to a preliminary report by the National Transportation Safety Board. The crew then saw fire and smoke and alerted dispatch of a possible derailment, the report said.

The axle investigators are focused on had been heating up as the train went down the tracks, but did not reach the threshold for stopping the train and inspecting it until just before the derailment, the report said. The train was going about 47 mph at the time, just under the speed limit of 50 mph, officials said.

Ohio Republican Lt. Gov. Jon Husted said ahead of the report’s release that its findings had the potential to form the basis of a criminal referral from the state. He also said railroad company Norfolk Southern should temporarily relocate people who continue to feel unsafe, or even consider buying their property.