Duterte cut short a visit to Russian Federation and placed the southern island of Mindanao under martial rule on Tuesday after a fierce bout of fighting erupted during a raid by security forces at a hideout of Islamic State-linked militants.
As gunfire crackled in the background, Herrera says authorities believe Isnilon Hapilon, who is on Washington's list of most-wanted terrorists, is still in the city.
Philippines President Rodrigo Duterte has imposed martial law on Mindanao Island, which includes Marawi, in an attempt to restore order.
A military spokesman says troops are using helicopters to help clear militants from the besieged city of Marawi in the southern Philippines.
On Thursday, Duterte assured government troops that he "alone" would be responsible for the "consequences" of his martial law declaration in the region.
Hapilon, who is a commander of the Abu Sayyaf militant group, pledged allegiance to the IS terror group in 2014. But the recent violence has raised fears that extremism could be growing as smaller militant groups unify and align themselves with the ideology of the Islamic State group.
The operation went wrong as the militants called in reinforcements and swept through the mostly Muslim city of 200,000 people. "We suspect there must be more who arrived separately", a Manila-based intelligence official told Sunday Mail.
Thousands of civilians have been fleeing.
Its activities are a source of concern for Mindanao native Duterte, who is familiar with separatist unrest but alarmed by the presence of radicals inspired by Islamic State's radical agenda.More news: Upset! Kerber 1st French Open top seed to lose in 1st round
More news: US State Department Says Syrian Regime Using 'Crematorium' To Dispose Of Bodies
More news: Who'll win? Cannes gears up for Palme d'Or prize night
Arrmanatha further said that the 10 JT members were hosted by an Indonesian citizen identified only as Yusuf, who was married to a local and had lived in Marawi for several years. "You can arrest any person, search any house without warrant", said Duterte, who has been criticized for the deaths of thousands of people in a crackdown on illegal drugs.
He said security forces in Marawi have also been ordered to secure areas around mosques to allow the Muslim faithful to visit and observe Ramadan.
"Right now, he is still inside (the city)", Gen. Eduardo Ano told The Associated Press.
Military intelligence said the Maute brothers also had links to two of the region's most risky militants - Indonesian Ustadz Sanusi and Malaysian bomb maker Zulkifli bin Hir, alias Marwan.
One local police chief told the AP on Friday that he was fine - two days after Duterte announced he had been beheaded by militants. "But we are certainly agreed that Martial Law must be temporary", Cotabato Archbishop Orlando B. Cardinal Quevedo said in a statement on Friday.
A woman touches an image of Jesus Christ shortly after attending a mass for victims of the recent attack in Marawi by Muslim militants linked to the Islamic State group and also for extrajudicial killings inside a church in Man.
With much of Marawi a no-go zone, confusion reigned.
The U.S. State Department has a bounty of up to $5 million for his arrest.
In 1972, late President Ferdinand Marcos declared a nationwide martial law that apparently paved way for alleged numerous deaths and human rights abuses.
"They have threatened to kill the hostages if the government forces unleashed against them are not recalled", said Father Socrates Villegas, president of Catholic Bishops Conference of the Philippines.