Separatist gunmen attacked a police station Tuesday in Indonesia's restive Papua province, killing three officers and setting the complex alight, police said.

Around 50 gunmen, said by police to be members of the separatist Free Papua Movement (OPM), attacked the Pirime police station in the town of Wamena, provincial police spokesman I Gde Sumarta told AFP.

"There was an attack on Tuesday on Pirime police station, which resulted in the death of three police officers," he said via text message, adding that investigations are continuing.

"A shootout broke out between police and the gunmen, who have since fled to the mountains," he said. National police spokesman Boy Rafli Amar told reporters in Jakarta the gunmen had seized weapons from the station.

"They seized three weapons – two rifles and a pistol belonging to the police chief," he said. "We know the group needed weapons to carry out attacks."

The Pirime police chief and another officer were found dead in their barracks, while a third was killed as he prepared to raise the Indonesian flag, Sumarta said. The police station was set alight and the officers' bodies were charred.

Amar said security had been strengthened at police stations and police were hunting down the perpetrators. "They have escaped to the highlands and chasing them is not easy," he said, referring to the mountainous centre of the province, a known separatist hub.

Gun attacks are not uncommon in resource-rich Papua, where poorly-armed separatist groups have for decades fought a low-level insurgency on behalf of the mostly ethnic Melanesian population.