An unknown number of orcas have sunk a yacht after ramming it in Moroccan waters in the strait of Gibraltar, Spain’s maritime rescue service has said, in the latest in a series of similar incidents involving the animals.

The vessel, Alboran Cognac, which measured 15 metres (49ft) in length and carried two people, encountered the highly social apex predators, also known as killer whales, at 9am local time on Sunday.

The passengers reported feeling sudden blows to the hull and rudder before the boat started taking on water. After alerting the rescue services, a nearby oil tanker took them onboard and transported them to Gibraltar. The yacht was left adrift and eventually sank.

The incident is the latest example of recurring orca rammings around the Gibraltar strait that separates Europe from Africa and off the Atlantic coast of Portugal and north-western Spain. Experts believe them to involve a subpopulation of about 15 individuals given the designation “Gladis”.