() A search-and-rescue operation was underway after a military helicopter crashed late Wednesday near Tacoma, Washington, with four Special Operations soldiers aboard, Army officials said.

The MH-60 Black Hawk helicopter went down in a rural area at 9 p.m. local time during a training mission that launched from Joint Base Lewis-McChord. The four service members aboard were from the 160th Special Operations Aviation Regiment.

“This remains an active, ongoing situation,” a statement from Army Special Operations Command said.

The crash sparked a small wildfire that had grown to one acre by Thursday morning, the Washington Department of Natural Resources said.

Thurston County Sheriff Derek Sanders said fire and heat conditions prevented deputies from continuing rescue efforts when they first arrived on the scene.

The Associated Press contributed to this report.