Two Japanese tourists were believed to have been murdered during a boat tour of small islands while visiting Palawan Province in the southwestern Philippines, police have said.

Officer Bernard Dalabajan of the Coron Municipal Station said Saturday that Yoshihiro Arai, 24, and Masaru Itani, 59, were believed to have been shot and killed on or near Cullion island, with their bodies cut into pieces and thrown into the sea.

Dalabajan was citing what police were told by the two Filipino drivers of the tour boat.

Arai and Itani had checked into the GMG Hotel Coron, Palawan on May 30, along with another 55-year-old Japanese national and 49-year-old Filipino translator before all four departed on an island-hopping boat tour.

According to the two boat drivers, at some point three other men joined the group and killed Arai and Itani during a stop on one of the islands.

“When they arrived at the island, they took them to an area where there are no people and shot them,” the drivers told police, according to Dalabajan.

Police were told that Arai was shot in the back of the head, before Itani was shot in the back and in the forehead. Police have released no details about the three men whom the drivers said killed the Japanese tourists.

Hotel staff reported the two missing on May 31, the day after the boat tour.

The third Japanese and Filipino translator also notified the authorities that the two men were missing, saying they had gone their separate ways at some point during the trip.

Dalabayan said the two boat drivers, the translator and the third Japanese man are all currently being held at the Coron Municipal Police Station.

He also said at least five search teams were looking for the bodies of the two missing tourists in the areas where the boat drivers had said to look.