A Wisconsin-based fighter pilot died after a plane crashed in a national forest in Michigan’s Upper Peninsula during a training mission, military officials said Dec. 10.

The Wisconsin Air National Guard’s 115th Fighter Wing announced the pilot’s death Dec. 10, but said the pilot’s identity will not be released until 24 hours after family members are notified.

The cause of the Dec. 8 crash wasn’t immediately known and is being investigated, officials said.

The plane was assigned to the Wisconsin Air National Guard’s 115th Fighter Wing at Truax Field Air National Guard Base in Madison. It went down in Hiawatha National Forest, about 250 miles northeast of the base. The crash site is in Delta County, which is located on the shores of Lake Michigan.

“We are deeply saddened by this tragic loss, and our thoughts and prayers are with the family during this difficult time,” 115th Fighter Wing Commander Col. Bart Van Roo said. “Today is a day for mourning, and the 115th Fighter Wing along with the entire Wisconsin National Guard stands with the pilot’s family as we grieve the loss of a great Airman, and patriot.”

“We are an extremely close knit group at the fighter wing, and the loss of one of our own brings immeasurable sadness to every member of our organization,” he said.

The 115th Fighter Wing participated in a coordinated search effort with local emergency responders, the U.S. Coast Guard and other government agencies.

The national forest spans about 879,000 acres, according to the forest’s website. The closest community to the crash site — a remote area with no cellphone service — is the small village of Steuben, located in adjacent Schoolcraft County, authorities have said.

The 115th Fighter Wing plans to provide more details on Dec. 11.