At least 22 combatants were killed in a bloody clash between a Muslim rebel group and Al Qaeda-linked militants in the volatile island of Sulu in southern Philippines on Sunday.

The Moro National Liberation Front, which signed a peace deal with the government, said it attacked the Abu Sayyaf at close range in the southern Sulu province of Patikul after the militants refused to release foreign hostages in negotiations.

“We had no choice,” rebel commander Khabir Malik told AP by telephone on Monday. “They told us they won’t hand over their hostages to us even if they die.”

The Moro rebels attacked the Abu Sayyaf with guns and knives, Malik said, adding his group lost eight men, including one who was beheaded and a few others who were hacked to death.

Military and police officials in Sulu said up to 14 Abu Sayyaf men were killed.

The hostages, including a Jordanian TV journalist and two European men who have been held since last year, remained in the hands of the Abu Sayyaf but there was no word on whether any of them were hurt in the fighting, police said.

The conflict subsided Monday after the militants split into smaller groups. But violence could erupt again, Sulu provincial police chief Senior Superintendent Antonio Freyra said.

Two Filipino hostages were released by the Abu Sayyaf over the weekend after an unspecified ransom was paid, according to security officials.

Sunday’s clash was the first major bloody confrontation between the two insurgent groups, which have fought side by side against government troops in the predominantly Muslim province.

The MNLF rebels signed an autonomy deal with the government in 1996 and has taken the initiative to seek the freedom of Abu Sayyaf hostages to help the government clean up the image of the conflict-riven province, AP reports.