A long-held Dutch hostage was shot and killed by his Abu Sayyaf captors Friday when he tried to escape during a gunbattle in the southern Philippines, military officials said.

Dutch birdwatcher Ewold Horn was fatally shot while trying to escape during a fierce firefight between the militants and army troops in the jungles of Sulu province's mountainous Patikul town, said military commander Brig. Gen. Divino Pabayo Jr.

At least six militants were killed and 12 others wounded in the nearly two-hour firefight. Eight soldiers also were wounded, the military said. Among those killed was the wife of Abu Sayyaf commander Radulan Sahiron, a militant long wanted by the United States and the Philippines.

Horn, a Swiss friend and a Filipino companion were abducted by gunmen during a birdwatching trip in Tawi Tawi province, near Sulu, in 2012. Horn's Filipino companion managed to escape shortly after their abduction while Swiss captive Lorenzo Vinciguerre dashed to freedom years later.

"We are angered by the ASG's utter disregard for human rights that they would rather murder Mr. Ewold Horn than let him be recovered by government forces," Pabayo said in a statement. Horn's body was recovered by government forces, he said.

He said that government forces "tried our very best to safely rescue him from his captors" and suffered casualties themselves.

The Abu Sayyaf, a small but violent group in the Muslim south of the largely Catholic Philippines, has been known for extortion, kidnappings, beheadings and bombings, and has pledged allegiance to Daesh militants in Iraq and Syria.

It earlier pledged allegiance to the al Qaeda militant group.