A MH-60 Black Hawk helicopter in Pacific Northwest camouflage.

The Army has now confirmed that four soldiers, based at Joint Base Lewis-McChord (JBLM), likely died when their MH-60 Black Hawk helicopter crashed around 9 p.m. Wednesday.

The aircraft, assigned to the 160th Special Operations Aviation Regiment (SOAR), went down in the heavily wooded hills above Summit Lake, about 40 miles southwest of JBLM and 20 miles west of Olympia.

Deputies from the Thurston County Sheriff’s Office located the wreckage Thursday morning. “We have been advised that the military lost contact with a helicopter in the area, and we are working closely with JBLM to assist,” the sheriff’s office said in a statement.

Jacqueline Hill, with the U.S. Army Special Operations Command Public Affairs Office, said the cause of what the military is referring to as an “aviation mishap” has not yet been determined.

Army Special Operations Command spokesperson Col. Allie Scott also noted the aircraft went down in “hard to reach” terrain. An investigation into the crash is underway.

The 160th SOAR — the “Night Stalkers” — is the Army’s elite aviation unit providing dedicated lift for special operations forces. The regiment has battalions at Fort Campbell, Kentucky; Hunter Army Airfield, Georgia; and JBLM. Its aviators are best known for flying Navy SEALs into Pakistan during the 2011 raid that killed Osama bin Laden.