Sens. JD Vance, R-Ohio, and Marco Rubio, R-Fla., are looking for answers after a massive train derailment in Vance's home state resulted in a fiery wreck and hazardous chemicals having to be released into the air.

In a letter to Transportation Secretary Pete Buttigieg, the Republican senators questioned whether the 150-car Norfolk Southern freight train was sufficiently staffed and whether Biden administration policies may have contributed to the situation.

"Current and former rail workers, industry observers, and reform advocates have pointed to precision-scheduled railroading (PSR), by which rail companies such as Norfolk Southern increase efficiency and drive down costs by moving more freight with fewer workers, as a potential contributor to the accident," the letter reads. "We have voiced concerns with PSR, as well as with this administration’s prioritizing of efficiency over resilience in its national infrastructure and transportation systems."

Fox News reached out to the Department of Transportation for comment, but they did not immediately respond.

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Rubio and Vance noted that the train that derailed in East Palestine, Ohio, had a three-member crew of a locomotive engineer, conductor and a conductor trainee to manage the 150-car train. The letter said that according to security camera footage, there were "sparks or fire underneath at least one of the cars before the derailment" when the train was about 20 miles outside of East Palestine. They said that "a mechanical failure in one of the rail cars" may have been the cause of the derailment.

The Republicans questioned whether two crew members and a trainee were enough to handle the 150-car train, and they noted that "derailments have reportedly increased in recent years, as has the rate of total accidents or safety-related incidents per track mile."

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While those numbers have gone up, labor costs have gone down, the senators said, adding that Class I rail companies have "shed nearly one-third of their workforce."

Rubio and Vance concluded by asking Buttigieg to give them information about what the Department of Transportation has done to protect against "reduced performance and resilience" from PSR, what effects PSR has had on U.S. steel rails, and PSR's effects on axle bearings' rate of overheating. 

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They also noted that the train that derailed had not been classified as a "high-hazard flammable train," even though it carried flammable material, and asked if the use of PSR warrants a potential change to how the classification is defined.

The senators gave Buttigieg 30 days to respond.