Sulu Sea: "Five fishermen shot dead in Philippine sea attack"

Not sure this is piracy or some sort of fishing turf war or something else, "Five fishermen shot dead in Philippine sea attack":

Gunmen aboard a speedboat shot dead five members of a fishing crew in a mysterious attack in the seas of the southern Philippines, the coast guard said Saturday.

The five were part of a fishing fleet off the troubled southern islands of Sulu when the gunmen attacked them on Friday, said coast guard spokesman Lieutenant Jomark Angue.

Even as the five leapt overboard, the gunmen riddled them with bullets, then sped off. Only three of the bodies were recovered, he said.

The attackers were suspected to be pirates Angue added. But it was unclear why they would attack the fishing boat crew.

Law-enforcement sources said the attack might be part of an extortion attempt by armed groups operating in Sulu, an impoverished, heavily-forested group of islands.