DUBAI, United Arab Emirates (AP) — Police in Oman say a cargo ship loaded with construction material has sunk off the sultanate’s southern coast, though all 20 sailors aboard the vessel were saved.

The Royal Oman Police on Sunday posted pictures online of sailors on a boat after being rescued, their sinking ship slipping beneath the waves of the Arabian Sea.

The police said on Twitter that the boat sank off the coast of Lakabi, a town some 620 kilometers (385 miles) southwest of the sultanate’s capital, Muscat.

It’s unclear what would have caused the boat to sink as the weather off Lakabi was calm Sunday.

The name of the ship and its owner were not immediately known. Police did not immediately respond to a request for comment from The Associated Press.