Eliseo Garcesa, mayor of Pigcawayan town, told Philippine radio he was still seeking information about possible casualties.
Pigcawayan is 120 miles south of Marawi City, where BIFF militants, along with fighters from other groups allied to the Islamic State group, have been holed up and fighting the Philippines military.
Nearly 350 people have been killed in the month of fighting, according to an official count.
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.
The seizure of Marawi and the dogged fight to regain control of it has alarmed Southeast Asian nations which fear Islamic State – on a backfoot in Iraq and Syria – is trying to set up a stronghold in the Muslim south of the mainly Roman Catholic Philippines that could threaten the whole region. – Telegraph