A helicopter crash in the eastern Mediterranean Sea on Friday night claimed the lives of five American service members who were in a training exercise, officials announced on Sunday.

U.S. European Command initially stated on Saturday that they were investigating the cause of the crash, but they ruled out any hostile activity.

The helicopter was on a “routine air refueling mission,” European Command said in their latest statement. They did not give any more details.

The identities of the deceased have not been disclosed yet, as they are waiting to notify their relatives.

Defense Secretary Lloyd Austin issued his own statement, saying that “this tragic crash reminds us of the courage and sacrifice of the men and women who serve our great nation and protect our safety every day. They are the best of America. We will honor their service and their memory.”

Austin also said, “I am praying for the heroes we have lost today and their families, friends, and colleagues.”

There was a discrepancy between the statements of European Command officials and Austin about when the incident happened, whether it was late Friday or early Saturday. The Pentagon clarified on Sunday afternoon that it was late Friday.

President Joe Biden expressed his sorrow for the deaths, saying in a statement that military members “risk their lives for our country every day. They courageously take chances to protect and serve the American people. And their daily heroism and generosity is a lasting tribute to what is best in our nation.”

Recognizing that the crash happened at the beginning of Veterans Day weekend, Biden said, “We once again reaffirm the sacred duty we have to those who choose to serve our nation as well as their families, caregivers, and survivors.”

“Jill and I are praying for the families and friends who have lost a dear one—a part of their soul. Our whole nation feels their pain,” the president said.