Crews are on the ground in and around the site of Monday's oil-train derailment in West Virginia deploying containment boom, the response team said.

The National Transportation Safety Board estimated 28 tank cars of the 109 from a CSX line slipped the rails early Monday afternoon near Mt. Carbon, W. Va. State authorities estimated about a dozen of those cars were transporting crude oil from North Dakota, which would equate to approximately 8,000 barrels.

A unified command set up by CSX, local, state and federal authorities said crews are on the ground surveying land and water contamination. No cars fell into the nearby Kanawha River.

"The response crews were able to deploy about 500 feet of containment boom as a precautionary measure to limit potential impact on the environment," the command center said in its latest update Wednesday. "The use of additional boom material is being evaluated."

West Virginia Gov. Earl Ray Tomblin declared a state of emergency for the areas in and around the derailment. At least one home was destroyed, minor injuries were reported and water supplies were disrupted as a result.

While the cause of the incident remains under investigation, NTSB regulators said the derailment, the latest involving the transportation of crude oil, raises additional safety concerns.

A string of derailments, including the deadly 2013 incident in Lac-Megantic, Quebec, sparked concerns over the use of rail cars designated DOT-111 to transport crude oil. The CSX cars were a newer model labeled CPC 1232.

Crude oil from North Dakota was characterized as more prone to explosion than other grades, though those in the industry were critical of the corresponding safety warning issued by federal regulators.