On 2 August 1981, the ship Primrose grounded on the North Sentinel Island reef. A few days later, crewmen on the immobile vessel observed that small black men were carrying spears and arrows and building boats on the beach. The captain of the Primrose radioed for an urgent airdrop of firearms so the crew could defend themselves but did not receive them. Heavy seas kept the islanders away from the ship. After a week, the crew were rescued by an Indian navy helicopter.