A preliminary report claims that the crew of a toxic train that crashed in Ohio attempted to slow the train down before it derailed.
According to federal investigators, the crew received a warning about a hot wheel bearing just before the incident.
Toxic chemicals were released as a result of the East Palestine train derailment on February 3.
Pete Buttigieg, the secretary of transportation, visited the area on Thursday.
The collision caused 38 cars to derrail, 11 of which were carrying hazardous materials. Later on, locals reported feeling ill as well as seeing dead fish and wildlife.
A wheel bearing on the train had heated up over a number of miles prior to the incident, according to the National Transportation Safety Board's (NTSB) preliminary report.
According to the report, it rose to a "threshold" level of 253F (122C) above the normal temperature just before the derailment.
The NTSB states that as the engineer applied the brakes, the train's automatic braking system was also activated, causing the train to stop and enabling emergency response to start.
The report stated that "after the train stopped, the crew noticed fire and smoke.".
The report, however, didn't go into great detail about what specifically led to the derailment or how successful (or ineffective) the response was.
By February 5th, the derailment's fires had been put out, but authorities were still worried that the five cars carrying 115,580 gallons (437,500 liters) of vinyl chloride, an odorless gas used to make PVC, might blow up.
A huge plume of black smoke was then released over the small town of East Palestine as a result of authorities burning the substance under controlled conditions.
The report, which is not final, also found no proof that the train was moving faster than the 80 kph (50 mph) speed limit.
The NTSB stated that its investigation was still ongoing and that its investigators would concentrate on the tank car's design and wheels, as well as the burning of the vinyl chloride and the accident response.
The NTSB report was made public on the same day that Pete Buttigieg, the US Transportation Secretary, visited East Palestine to speak with residents and investigators.
Prior to his trip, Mr. Buttigieg had come under growing fire from both ends of the US political divide for what some perceived as a tardy response to the train derailment in East Palestine.
The company that operated the car, Norfolk Southern, as well as state and federal officials received criticism from many in the town for their allegedly inadequate response and lack of transparency.
Marco Rubio, a Republican senator, described him as "an incompetent who is focused solely on his fantasies about his political future," adding that he "needs to be fired.".
In an interview with CBS News earlier this week, Mr. Buttigieg defended his response and claimed that he had postponed his visit so that the NTSB could concentrate on its inquiry.
"In the early days following the crash, I have followed customary practice for transportation secretaries, letting NTSB lead the safety work and staying out of the way," he said.