GEORGETOWN, Guyana (AP) — Guyana’s government said Thursday that five military officers aboard a helicopter that crashed near the border with Venezuela have died and two others survived.

The military helicopter had vanished Wednesday about 30 miles (48 kilometers) east of the Venezuelan border during bad weather while transporting officers carrying out a routine inspection of troops in the forested area. Searchers found the wreckage Thursday.

“My heart pains and drowns in sorrow at the tragic (loss) of some of our finest men in uniform,” President Irfaan Ali said in a statement posted on social media, calling the loss “immeasurable.”

Ali identified those who died as a retired brigadier general, a colonel and two lieutenant colonels. The two survivors include the co-pilot, and their conditions weren’t immediately known.

Prime Minister Mark Phillips said authorities are still trying to determine what caused the helicopter to crash, with officials stressing during a news conference Wednesday that there was no indication to suggest any hostile fire.

“We have to find out what happened. The search and rescue has now transitioned to a search and recovery,” Phillips told The Associated Press.

Army Chief Brig. Gen. Omar Khan told reporters late Wednesday that Guyana’s Defense Force lost contact with the brand new Bell 412 EPI aircraft after it took off from Olive Creek settlement in western Guyana following a refueling stop.

The crash in the mountainous and heavily forested area is the worst in Guyana’s military history.

It occurred during an escalating diplomatic row with Venezuela over a vast region known as Essequibo, which is rich with minerals and located near massive oil deposits. The region abuts the border with Venezuela, which claims Essequibo as its own.