MANILA, Philippines (AP) — Two Russian tourists died when they were swept away by strong undercurrents while scuba diving in waters south of Manila, with one believed to have drowned and the other attacked by sharks, a Philippine coast guard official said Friday.

Two other Russian tourists managed to swim back safely to their dive boat Thursday off Verde Island, a popular diving destination in the province of Batangas, Philippine coast guard provincial commander Capt. Airland Lapitan said.

The four Russian tourists traveled by boat to the waters off Verde Island from the nearby town of Puerto Galera in Oriental Mindoro province with a Filipino dive instructor. While diving, the five were swept away by strong undercurrents, Lapitan said.

Two of the Russians managed to surface with the dive instructor but the two other Russians, who were identified as Ilia Peregudin, 29, and Maksim Melekhov, 39, went missing. The dive instructor and other divers in the area, along with Philippine coast guard personnel, immediately launched a search, according to Lapitan.

Melekhov was found unconscious at sea an hour later and was declared dead by doctors in a Batangas hospital, he said.

“The other Russian diver was found while being attacked by sharks. His right arm, unfortunately, had been severed and the sharks were moving around him,” Lapitan told The Associated Press. “They somehow managed to pull him away.”

An investigation is underway and the coast guard will meet provincial officials to discuss ways to prevent such deadly incidents at Verde Island and other dive spots, Lapitan said.