Indonesian security forces on Saturday found the bodies of four construction workers killed in a separatist attack in the restive province of West Papua, police said.

The four men were killed on Thursday evening when gunmen stormed a government road construction project in the remote village of Meyarga in Bintuni Bay district, the Papua Police spokesman said. West, Adam Erwindi.

Five other workers fled to a nearby military post, one of whom was injured in the attack, while three others hid in the jungle. The lone worker managed to escape and is still missing, Erwindi said.

He said the bodies had been guarded by the gunmen until security forces found them on Saturday. Two of the remains were charred near two heavy equipment and three trucks that were set on fire by the attackers, and the other two sustained gunshot and stab wounds, Erwindi said.

“We believe this attack was launched by the armed separatist criminal group amid intensified government efforts,” Erwindi said. He said the police and military were looking for the attackers, who authorities said belonged to the West Papua Liberation Army, the military wing of the Free Papua Organization.

The victims were among dozens of construction workers employed by a local construction company to build roads linking Bintuni Bay and Maybrat districts.

Rebel spokesman Sebby Sambon confirmed that the group’s fighters carried out Thursday’s attack. He said the group had warned all workers to leave Indonesian government projects or they would be considered part of the security forces.

“We don’t want construction by the colonizers, we can do it ourselves if we are given independence,” Sambom said in a statement sent to The Associated Press on Saturday. “The West Papua Liberation Army is responsible for this attack.”

He said the workers were considered foreigners by the separatists and were part of Indonesia’s intelligence services.

The Indonesian government, which for decades has had a policy of sending Javanese and other Indonesians to settle in Papua, is trying to stimulate economic development to curb the separatist movement.

Papua is a former Dutch colony in the western part of New Guinea which is ethnically and culturally distinct from much of Indonesia. Conflicts between indigenous Papuans and Indonesian security forces are frequent.

Papua was incorporated into Indonesia in 1969 after a UN-sponsored ballot that was widely seen as a sham. Since then, a low-level insurgency has been simmering in the region, which is divided into two provinces, Papua and West Papua.

In March, armed rebels killed eight technicians who were repairing an isolated telecommunications tower. In December 2018, at least 31 construction workers and a soldier were killed in one of the worst attacks in the province.

Attacks have increased over the past year, killing dozens of rebels, security forces and civilians.