Philippine troops killed at least 11 Abu Sayyaf militants, including an influential commander, in an assault on the extremists Friday following their beheading of a captive whose family was too poor to pay ransom, the military said.

Regional military commander Maj. Filemon Tan said 17 soldiers were wounded when hundreds of army troops surrounded a vast jungle area in Sulu province’s mountainous Patikul town and clashed with scattered groups of about 100 militants.

Among the 11 dead militants was Amah Maas, a longtime commander of the group who had severed arms and had been implicated in ransom kidnappings, including of European tourists.

President Rodrigo Duterte ordered the troops to destroy the militants in their jungle bases after the extremists on Wednesday beheaded a Filipino teenager, Patrick James Aldovar, who was abducted near a police camp in Sulu’s main Jolo town last month.

Thousands of reinforcement troops have been flown by C130 cargo planes to Sulu and nearby Basilan island to help in the ongoing offensive. Many of the troops were freed up from other combat zones in the country after Duterte declared an indefinite ceasefire last week with communist rebels, who are engaged in peace talks with the government brokered by Norway.

The Abu Sayyaf has been blacklisted as a terrorist organization by the U.S. and the Philippines for deadly bombings, kidnappings and beheadings. Without any known foreign funding, the extremists have relied on ransom kidnappings, extortion and other acts of banditry and some commanders have pledged loyalty to the Islamic State group partly in the hope of obtaining funds.

The militants are still holding several foreign and local hostages in their jungle bases, including Norwegian Kjartan Sekkingstad, who was kidnapped along with two Canadian men and a Filipino woman from a southern marina in September last year. The Canadians were beheaded after huge ransom demands were not met and the woman was freed before Duterte assumed the presidency on June 30.

During a news conference Thursday, Duterte suggested the militants may be continuing to hold Sekkingstad despite being paid a 50 million-peso ransom ($1-million) for his freedom.

Around the time the ransom was paid, the Filipino captive from the marina, Marites Flor, was instead freed by the Abu Sayyaf, two security officers told The Associated Press on condition of anonymity because they were not authorized to discuss details of the hostage talks publicly.

Presidential spokesman Ernesto Abella said the government was not involved with the payment and added the money was raised by “third parties,” which he did not identify. The government, he said, maintains a no-ransom policy in resolving kidnappings.

“We don’t encourage,” he said. “If they make negotiations, that is their negotiation.”