MANILA (Updated) -- Isnilon Hapilon and Omarkhayam Maute, the two final surviving leaders of a deadly siege in Mindanao, were killed in one of the final battles by thousands of troops to retake the last area in Marawi City, security officials said.

Their bodies were recovered by the troops Monday, October 16, said Presidential Spokesperson Ernesto Abella.

"We confirm that government forces killed Omar Maute and Isnilon Hapilon early morning today, Monday, the 16th of October, in Marawi City. Our operating units have already recovered their bodies," he said.

Defense Secretary Delfin Lorenzana said President Rodrigo Duterte and other officials were supposed to go to Marawi Monday, but their trip were postponed after the military said it will conduct an assault Monday.

“So following their operational plan, they were able to do it this morning,” he said in a press conference Monday.

He said that based on initial information, Hapilon and Maute were killed in a ground operation after the military got information about their exact location from a hostage who was able to escape.

Lorenzana said the killing of the two leaders indicates that the Marawi siege is about to end and it will help eradicate the Islamic State (IS) particularly in the country.

Maute brothers Omar and Abdullah were reportedly the frontrunners of the extremist group that laid siege to Marawi City, Lanao del Sur, on May 23 while the military was conducting a manhunt operation against Hapilon, leader of Abu Sayyaf bandit group who was purportedly delegated as IS honcho in Southeast Asia.

The Maute brothers allegedly pledged fealty to IS fighters who sought to establish a caliphate in Mindanao for its Southeast Asia group.

Duterte, in an attempt to squelch insurgency and foil possible spillover to other parts of the country, declared martial rule, which is effective until end of December 2017.

But more than 1,000 people have been killed in the Marawi violence, including more than 800 terrorists. Army Colonel Romeo Brawner said Sunday, October 15, that about 40 terrorists were still fighting in a small residential area by Lanao Lake, including 100 relatives of the gunmen and civilian hostages.

Amid the ongoing armed conflict, Abella said the security forces were able to rescue 17 individuals, including an infant and women, held hostage by the terrorists. US-trained army and police commandos crawled toward the terrorists' positions overnight and launched an assault.

“Mopping up operations are now underway. Details of the operation will be released by the AFP as soon as permissible,” said Abella.

He said the public can expect an announcement of end of hostilities in war-torn Marawi once the state forces are able to completely flush out the remaining extremists and remove improvised explosive devices and other traps in all facilities.

“Once the fighting stops and the clearing operations end, we will put our efforts and energies on the challenging task of rebuilding and rehabilitating Marawi,” he added.

Lorenzana said they will announce within the week the cessation of hostilities in Marawi City.

“And then after that, we will find out, we will assess what the entire Mindanao if there is a need to recommend to the President the lifting of martial law,” he said, adding that they will prepare for the possible retaliation of the terrorist group's allies from Basilan, Sulu and several parts in Mindanao.

He added that Hapilon and Maute will be subjected to the DNA testing considering the bounty for each head - P5 million for Maute and over $5 million for Hapilon.

Earlier, the Armed Forces of the Philippines reported the killing Maute’s three brothers, namely Abdullah, Madi and Otto, based on the account of arrested Maute members and surrenderers. But Lorenzana said troops are yet to recover their bodies.

He said there is remaining one bandit who may now be serving as the group’s leader, Doctor Mamud from Malaysia.

The Marawi siege has sparked fears that the IS group may gain a foothold in Southeast Asia by influencing and providing funds to local bandits as it suffers battle defeats in Syria and Iraq. The United States and Australia have deployed surveillance aircraft to help Filipino troops battling the Marawi attackers. (With AP/SunStar Philippines)