Two U.S. Navy aviators who were flying an EA-18G Growler jet in Washington state when it crashed Tuesday were pronounced dead Sunday, the service said in a statement.

The announcement came after days of searching and efforts to reach the wreckage in a remote mountainous area west of Yakima. The Navy said the names of the two airmen would not be released until 24 hours after their next of kin were notified, and that the cause of the crash was under investigation.

“It is with heavy hearts that we share the loss of two beloved Zappers,” said Cmdr. Timothy Warburton, commander of Electronic Attack Squadron 130, said in the release, referring to the two sailors by the squadron’s nickname. “Our priority right now is caring for the families of our fallen Airmen and ensuring the well-being of our Sailors and the Growler community.”

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The Navy launched search and rescue efforts shortly after the Growler went down Tuesday, and the next day two of its own squadrons, the Whidbey Island Search and Rescue Teams and an Army Air Cavalry squadron from neighboring Joint Base Lewis-McChord, as well as local and tribal authorities in Yakima County, all participated in the search.

When the plane wreckage was finally located Wednesday afternoon, the Navy said it needed the specialized mountaineering experience of soldiers from the 1st Special Forces Group (Airborne), based at Lewis-McChord , to reach the site.

The plane had crashed at an altitude of 6,000 feet in a steep, densely forested area east of Mount Rainier, forcing rescuers to contend with mountainous terrain, cloudy weather and low visibility.

Despite the loss of the crew, the Navy said it would continue to “search the large area, recover debris, and plan for long-term rescue and recovery efforts.”

Growler Squadron, based at Naval Air Station Whidbey Island, had just returned from a combat deployment aboard the aircraft carrier USS Dwight D. Eisenhower.

This deployment included combat operations against Houthi rebels in Yemen. The Eisenhower, along with its support ships, conducted strikes and defended against missile attacks as the Houthis attempted to strike merchant ships in the Red Sea.

The Zapper squadron distinguished itself, and upon its return this summer, a Navy release noted that one of its pilots had achieved the first air-to-air victory over a Growler in Navy history, and that it was also the first squadron to use an Advanced Anti-Radiation Guided Missile, or AARGM, in combat.

The accident appears to be the first major incident involving a Navy aircraft this year.

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