(NewsNation) — All five Marines aboard a helicopter that crashed in California are dead, the Marine Corps announced Thursday.

“To the families of our fallen Marines, we send our deepest condolences and commit to ensuring your support and care during this incredibly difficult time,” Maj. Gen. Michael Borgschulte said in a statement posted on X.

The Marines’ names have not been released, pending family notification. They were with Marine Heavy Helicopter Squadron 361, attached to Marine Aircraft Group 16 with the 3rd Marine Aircraft Wing.

The helicopter crashed during a routine training flight from Creech Air Force Base near Las Vegas en route to Air Station Miramar in San Diego.

Turbulent weather was recorded in the area prior to the helicopter’s disappearance. The plane was reported overdue at 1:00 a.m. Wednesday and Cal Fire was alerted at 2:20 a.m.

The helicopter was found Wednesday morning near Pine Valley, California, but search crews were still searching for the five Marines aboard the aircraft even after locating it.

The search was hampered by snow and difficult terrain.

The Marines were flying in a CH-53E Super Stallion helicopter, which has roughly twice the accident rate of other helicopters. The large, heavy craft can carry up to 55 people and is used to carry heavy equipment and supplies, with the capacity to lift 16 tons.

The CH-53E has a record of crashes, some of them deadly. In 2016, two CH-53Es crashed into each other during a training exercise near Hawaii, killing 12 Marines. In 2018, a CH-53E crashed during training in California, killing four Marines.

In 2014, CH-53E crashed while trying to land on a transport dock at sea, however, all 25 people on board survived.

This is a developing story. Check back for updates.