Members of the BIFF were engaged in a gun battle with the military, the police chief at Pigcawayan, Chief Inspector Realan Mamon, said in a radio interview.

“We can confirm that they occupied a school and there were civilians trapped. We are in the process of determining how many were trapped and their identities,” Mamon said.

Government forces managed to push back the initial jihadist attack, but the IS-linked fighters managed to take at least five people hostage as they retreated, according to a spokesperson for the Army’s 6th Infantry Division.

“But as they (BIFF fighters) were escaping, they took some civilians hostage and [used them as] human shields,” Capt. Arvin Encinas, told the Philippine Daily Inquirer.

Pigcawayan is 190 kilometres south of Marawi City, where BIFF militants, along with fighters from other groups allied to IS, have been holed up and fighting the Philippines military since May 23.

Eliseo Garcesa, mayor of Pigcawayan town, told Philippine radio he was still seeking information about possible casualties.

President Rodrigo Duterte declared a state of emergency on the southern island last month after IS-linked fighters laid siege on Marawi City.  

“Although the situation in Pigcawayan may not be directly linked to the fighting that has been raging in Marawi for the past few weeks, it may have something to do with the martial law that been imposed across the region,” Al Jazeera’s Jamela Alindogan reported.

Philippine aircraft and troops launched a renewed push against the militants in Marawi City on Tuesday and a military spokesman said the aim was to clear the area by the weekend Eid festival, although there was no deadline.

Army spokesman Brigade General Restituto Padilla told Al Jazeera it was possible the attack was intended to disrupt the ongoing military offensive in Marawi.