Two sheriff’s deputies were fatally shot and two others were wounded Sunday in Buchanan County in far southwestern Virginia, state police said.

One of the wounded deputies appeared to be in critical condition, according to the state police.

The four deputies were all shot by a single assailant, who was later found dead, a state police spokeswoman said. It was not immediately clear Sunday night how he died or where he was found, and authorities were still working to confirm his identity.

The shooting occurred shortly after 2 p.m. when deputies were sent to a salvage yard in the Vansant community, where a larceny was reportedly in progress, state police said.

The exact sequence of events was under investigation Sunday night, said Corinne Geller, the state police spokeswoman.

She said the first two deputies to arrive were shot and killed. When two others got there, the assailant fired at them, Geller said. It was not clear how far away he was, or what kind of weapon he used.

The more seriously injured of the two wounded deputies was flown by state police helicopter to the Bristol Regional Medical Center in Bristol, Tenn., Geller said said.

The other deputy was taken by ambulance to a hospital in the Buchanan County area and was reported to be in serious condition.

Coal mining is a major economic activity in Buchanan County, about 400 miles southwest of Washington. The road on which the salvage yard is located winds between steeply pitched hills.

The town of Grundy, about a half-dozen miles north of Vansant, is the county seat of Buchanan County and the home of the Appalachian School of Law. A former student at the school killed three people and wounded three with a pistol there nine years ago.

The man was subdued by armed students and was later diagnosed as having paranoid schizophrenia. He was sentenced to six life terms.