This is a developing story.

A helicopter crashed in Washington state near Joint Base Lewis-McChord, the U.S. Army said Thursday. There was no immediate word of how many people were aboard and their conditions.

The helicopter crashed at about 9 p.m. Wednesday near the base, an Army official said in a statement.

“This remains a developing situation, and no additional details are available at this time,” the statement said. No details were released about the helicopter.

The base is about 10 miles (16 kilometers) south of Tacoma under the jurisdiction of the U.S. Army Joint Base Headquarters.

The Thurston County sheriff’s office, based in Olympia, posted online late Wednesday that deputies were dispatched to reports of a possible helicopter crash in the Summit Lake area, west of Olympia.

“We have been advised that the military lost contact with a helicopter in the area,” the department said. It said it was working with the base and that no further details were available.

Thurston County Sheriff Derek Sanders said on Facebook that deputies located the crash site, “but have been unable to continue rescue efforts as the scene is on fire.”

The King County Guardian 1 helicopter and special operation rescue units responded to the crash site, the sheriff said.