Kurniawan Hari, Jakarta – Three days after a group of armed men killed two American school teachers and an Indonesian in an ambush at a location that is normally tightly controlled by police and soldiers in Papua, the police are as yet in the dark as to who the perpetrators were.

National Police chief Gen. Da'i Bachtiar said that his men were still evaluating all the evidence and were as yet unable to conclude whether the perpetrators were members of the Free Papua Organization (OPM).

"We don't know exactly. We are still assessing the situation," Da'i told the press on the sidelines of a hearing with the House of Representatives's foreign and defense committee here on Tuesday.

Two Americans and an Indonesian – all the employees of PT Freeport Indonesia – were killed in the incident on Saturday, while 12 others were injured.

Meanwhile, the United States Embassy in Jakarta condemned the "senseless attack on unarmed civilians" in Papua. "We extend our sincere condolences to the families of those killed and our concern for those who were injured in the attack," the embassy said in statement.

The attack on the innocent victims, who were mostly schoolteachers, was an outrageous act of terrorism, it said. "We urge the government of Indonesia to take all necessary steps swiftly to apprehend and punish the perpetrators of this horrible attack," it said.

The attack was surprising, considering that the location is tightly controlled by the military and police.

Security forces shot dead a suspected rebel in a gunfight one day later as they hunted for the armed men who killed the employees of PT Freeport Indonesia. Da'i said that residents living in the vicinity did not recognize the suspected rebel after being shown his body.

Local residents, according to Da'i, said that the dead man had similar physical characteristic with the gunmen that launched the attack on Saturday. "Local residents don't recognize the body. Possibly, he is a newcomer," Da'i added. However, residents in the village of Banti Tembagapura wanted to take the body for burial, prompting speculation that the suspected rebel was a local resident.

Human rights activists suspect that military personnel might be involved in the attack and called for the establishment of an independent inquiry to investigate the incident.

The Papuan people's trust in the security forces is at a low ebb as the latter have been unable or unwilling to uncover those behind the murder of Papuan independence leader Theys Hiyo Eluway in November last year.

During the hearing, led by foreign and defense committee chairman Ibrahim Ambong, the police chief related the chronology of the bloody incident to committee members.

Da'i said that the bullet casings showed the gunmen had used M-16 automatic and SS1 semiautomatic rifles. "We'll keep on chasing the attackers," he said. He brushed aside demands for the government to set up a special investigation. "We will continue what we have been doing to date," he said.