Government forces are scrambling to rescue the remaining hostages of Islamic State-linked terrorists in Marawi, whose firepower has started to sputter some 4 months after they laid siege to the southern city, a military official said Sunday.

"Mukhang humihina na po sila (mga terorista) dahil pailan-ilan na lang ang putok na galing sa kanila," Col. Romeo Brawner, deputy commander of the Joint Task Force Marawi, told DZMM.

"But they still pose a danger, a threat dahil nga po may hawak pa silang mga bihag at ginagamitan nila ng improvised explosive devices dito sa main battle area."

The military rescued Wednesday 17 hostages, some of whom were forced to fight alongside extremists, said Brawner.

The rescue, which sources said brings down the number of remaining hostages to around 20, comes days after Armed Forces of the Philippines requested for an extension to liberate the war-torn city.

Terror leaders Isnilon Hapilon and Omarkkhayam Maute are still inside the battle zone, Brawner said, citing information from rescued captives.

More than 800 people, mostly terror suspects, have been killed in the fighting in Marawi, which also left much of the once urban and cultural center in ruins, with buildings either burned to the ground or damaged in firefights.

It also spawned a humanitarian crisis with more than 400,000 people displaced from Marawi and nearby towns.

• Why has the Marawi crisis dragged on for months?

DZMM, 5 October 2017