Sen. Sherrod Brown (D-Ohio) on Thursday called on Ohio Gov. Mike DeWine (R) to declare a disaster following the derailment in East Palestine of a train containing several cars of hazardous chemicals.

In a letter, Brown praised DeWine’s handling of the incident but called for a formal declaration from the governor’s office to allow the state to request federal aid in the cleanup process.

“A man-made disaster of this scale, scope, and significance necessitates a response and deployment of resources that are commensurate in scale and scope,” Brown wrote. “I’m grateful for all that the Ohio Environmental Protection Agency, U.S. Environmental Protection Agency, Ohio Emergency Management Agency, local fire fighters, and local law enforcement have done to respond to this unprecedented disaster, but it’s critical we act quickly to supplement those efforts. Additional federal resources can and should play a critical role in helping our fellow Ohioans get back on their feet and ensure that their community is a safe place to live, work, and raise a family.”

The train, operated by the Norfolk Southern railroad, derailed Feb. 3 in the town on the Pennsylvania border, spilling various substances including vinyl chloride, a toxic chemical used to produce plastics. Officials evacuated the town but allowed residents to return days later.

State officials have said the air and the water remain safe after testing. However, observers and residents remain particularly concerned about potential contamination of the Ohio River, which provides drinking water to millions of people. Local officials have confirmed at least 3,500 fish have died since the spill.

In a press conference Wednesday, DeWine said President Biden has offered any assistance the state needs but that the governor had deemed it unnecessary at this stage. EPA Administrator Michael Regan traveled to the town and is set to deliver remarks Thursday.

In a statement, DeWine’s office said “FEMA continues to tell Governor DeWine that Ohio is not eligible for assistance at this time. Governor DeWine will continue working with FEMA to determine what assistance can be provided.”

The office of Brown’s fellow Ohio Sen. J.D. Vance (R) referred The Hill to comments the GOP senator made in East Palestine to WKYC Channel 3 in which he said it was also important to “not let Norfolk Southern off the hook,” saying “we have to be careful about” a course of action that would transfer liability entirely to the federal government, “but I would say my main emphasis is, we need to get this community the resources necessary to rebuild.”

Updated at 1:29 p.m.