U.S. Forest Service and transportation safety officials returned today to the Sabine National Forest as they continued investigating a helicopter crash that killed three people.

The Bell Model 206-B3 helicopter was operating under contract with the Forest Service, officials said.

One of those killed in Thursday’s crash was the forest's fire management officer, 54-year-old Charles Edgar.

Also killed were John Greeno, 51, Bald Mountain heliport manager with the Mi-Wok Ranger District on the Stanislaus National Forest in California and pilot Jose Victor Gonzalez, whose age was not provided.

The helicopter crashed Thursday during prescribed burning operations in the forest.

As a precaution, the Forest Service grounded aviation operations in the national forests and grasslands in Texas.

The move delayed scheduled burning, but officials said the delay shouldn't endanger any forest areas.

The Sabine National Forest in southeast Texas drew attention in early 2003 as an area where shuttle "Columbia" recovery efforts were concentrated.

All seven astronauts died when Columbia broke apart and burned during re-entry.