House Oversight Committee lawmakers launched an investigation into Department of Transportation Secretary Pette Buttigieg over his "apathy" in the face of the dangerous train derailment in East Palestine, Ohio, after the secretary waited 20 days to visit the site after the initial wreck.

About 50 rail cars operated by Norfolk Southern, including 10 carrying toxic chemicals, derailed on the evening of Feb. 3 in East Palestine, a small town on the Ohio-Pennsylvania border. Officials conducted a controlled release of vinyl chloride from some of the cars three days later to avoid an explosion, sending hydrogen chloride and phosgene into the air.

Buttigieg came under fire from local residents and lawmakers for waiting over a full week to publicly acknowledge the incident.

In a letter to Buttigieg Friday, the House Republicans demanded documents and information related to the department's response to the disaster.

OHIO RESIDENTS ERUPT AT TOWN HALL: 'WHERE'S PETE BUTTIGIEG?'

Pete Buttigieg

White House officials, including Transportation Secretary Pete Buttigieg, center, are calling for higher fines for railroad safety violations following their visit to the Norfolk Southern crash site in East Palestine, Ohio. (AP Photo/Matt Freed)

"The Committee on Oversight and Accountability is investigating the ongoing crisis that began on February 3, 2023, in East Palestine, Ohio," the letter states. "A Norfolk Southern freight train’s derailment and the ensuing response released highly toxic chemical materials into the air, water, and soil — forcing residents of East Palestine to evacuate. This incident is an environmental and public health emergency that now threatens Americans across state lines."

BUTTIGIEG VOWS TO ‘HOLD NORFOLK SOUTHERN ACCOUNTABLE’ AS CRITICISM MOUNTS OVER RESPONSE TO TRAIN DERAILMENT

Pete Buttigieg at Ohio press conference

Transportation Secretary Pete Buttigieg, right, admits during a press conference that he waited too long to make a public statement on the Norfolk Southern train derailment in East Palestine, Ohio on Thursday, Feb. 23, 2023.   (WKBN)

"Despite the U.S. Department of Transportation’s responsibility to ensure safe and reliable transport in the United States, you ignored the catastrophe for over a week. The American people deserve answers as to what caused the derailment, and DOT needs to provide an explanation for its leadership’s apathy in the face of this emergency," they wrote.

During his first visit to the site of the Norfolk Southern train derailment Thursday, Buttigieg admitted that he waited too long to address the accident.

PETE BUTTIGIEG FACES CALL TO RESIGN AFTER EAST PALESTINE DISASTER: ‘SERIOUS AND PERSISTENT PROBLEMS’

Buttigieg speaking

Transportation Secretary Pete Buttigieg speaks during a news conference near the site of the Norfolk Southern train derailment in East Palestine, Ohio, on Thursday, Feb. 23, 2023. (Matthew Hatcher/Bloomberg via Getty Images)

"The answer to your question is yes," Buttigieg said, acknowledging that letting a week and a half go by before tweeting about the train derailment was too long. He told reporters he had tried to "balance" his desire to get involved with the "norm of transportation secretaries" — which is to permit the proper regulatory authorities to work without his interference.

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Buttigieg has also vowed to "hold Norfolk Southern accountable" in a letter sent to the company's CEO Alan Shaw.