MANILA - Extremists holed up in Marawi are expected to surrender en masse following the state offensives that killed their top leaders, Omar Maute and Isnilon Hapilon, a local official said Monday.

Soldiers neutralized Maute and Hapilon after a female hostage who escaped helped locate their hideout.

"Iyung ranks, fighters po nila mawawalan po ng morale. Of course, they are the leaders," Zia Alonto Adiong, spokesperson of the Lanao Del Sur crisis management committee, told DZMM.

"We expect that there will be substantial number of surrenderees from their ranks at talagang magwi-weaken na po talaga ang hold ng grupong ito," Adiong said.

Adiong added that the terrorists' hold on Marawi is slipping, as evident the escape of their 17 hostages late Sunday.

"Ito po iyung nagsi-signal na patapos na po talaga iyung giyera. Patapos na po ang paghihirap ng mga bakwit," he said.

(This signals that the war is almost over, that the suffering of evacuees is almost over.)

Malacañang had announced a P5 million bounty for the "neutralization" of each of the Maute brothers, and P10 million for Hapilon.

A separate $5 million bounty was also offered for the arrest of Hapilon, an Abu Sayyaf leader who was said to be the anointed ISIS leader in Southeast Asia. The Marawi clashes supposedly started when troops tried to serve an arrest warrant on Hapilon.

Islamic State-linked gunmen occupied parts of Marawi, the Islamic capital of the mainly Catholic Philippines, on May 23. Since then more than 1,000 people had been killed and 400,000 residents displaced.

Troops were still pursuing Malaysian militant leader Mahmud Ahmad in the Marawi battle zone, Defense Secretary Delfin Lorenzana said. Ahmad had helped plan the Marawi attack, authorities had said.

The insurgents have withstood a relentless bombing campaign and intense ground battles with troops that have left large parts of Marawi resembling devastated cities in war-torn Syria and Iraq. With Agence France-Presse and Jamaine Punzalan, ABS-CBN News