Sea and breaking waves by Los Gigantes in Tenerife,/Spain. Mika Volkmann/Getty Images

two men and two women - died and another person is missing after a powerful wave dragged a group of swimmers out to sea while swimming at a popular seawater pool along the coast of the Spanish island of Tenerife, officials said Monday.

Emergency crews recovered three bodies on Sunday - a 35-year-old woman, a 55-year-old man and another man about whom no information was given - during a major rescue operation. The fourth, a woman, died Monday, a day after she was revived at the scene and airlifted to a hospital.

Another person was still in the hospital, while the authorities were searching for another missing person, a spokesperson for the emergency services told Agence France-Presse.

No additional information about the identities of the victims was provided. However, Slovakia`s foreign ministry said in a statement it "has been informed of the death of two Slovak citizens" in the incident, while Bucharest first confirmed the death of one citizen, and later that of the second.

The pool at Isla Cangrejo, on Tenerife`s Los Gigantes coast, is very popular with foreign vacationers, according to local media. Bordered by volcanic rock on one side and cemented off from the sea on the other, the pool sits at nearly sea level and can be very dangerous during rough seas when large waves can easily overcome the cement barrier.

Local media reported that a weather advisory for rough seas was in effect at the time when the swimmers were swept out to sea. One media outlet reported that the pool had been closed to swimmers since Dec. 3.

A witness told local media that two strong waves took everything in their path, El País reported.

"We were very far away (from the pool) and even then, the waves reached us," they said. "I looked backwards and the pool went from being full to having no one."

Area residents said swimmers had ignored signs and fencing put up to prevent anyone from going into the pool because of the weather conditions. They said it`s very difficult for anyone dragged out to sea to get a foothold on slippery rocks just below the pool.

"People ... don`t know how the sea is here, and the danger of the pool, because there are rocks below on which people fall and can`t get back up. It`s very dangerous," said one area resident who didn`t give his name.

Emilio Navarro, the mayor of Santiago Del Teide, offered his condolences to the families of the dead and said rescue crews continued Monday to search for the missing swimmer.

He said authorities take steps to warn bathers of the dangers and to dissuade them from using the pool during rough seas.

"We ... ask people to pay attention to the signage put up by the authorities," he said. "It`s to take care of and protect everyone."

Three people died, and at least 15 were injured, last month in similar incidents in Tenerife.

A woman died after being pulled into the ocean near the Puerto de la Cruz resort and a man died at Santa Cruz de Tenerife, CBS News partner the BBC reported at the time. A third man was found dead in the ocean near a beach in Granadilla.

Tenerife is the largest of Spain`s Canary Islands, off West Africa.