MANILA, Philippines - A day after a raging battle broke out between Filipino government troops and Islamist militants in the country's restive south, Philippine President declared martial law in the region.
Rodrigo Duterte, who had to cut short a trip to Russia and rush back home to deal with the growing violence, said in a news conference that the move was necessary in order to fight militants there.
He said, "I had to declare martial law in the Mindanao group of islands. It is our constitutional duty to enforce the law and provide security."
Duterte's order covers both the city of Marawi and the wider island of Mindanao, of which Marawi is a part.
He added, "If I think that the ISIS has already taken foothold also in Luzon and terrorism is not really far behind, I might declare martial law throughout the country to protect the people."
On Tuesday, fighting between government forces and the Maute group, an Islamist militant organization based in Mindanao, began in Marawi, that houses 200,000 people.
In a statement released in its affiliated media agency, Amaq, ISIS announced that "fighters of the Islamic State launch a wide-scale offensive on positions of Philippine troops in the city of Marawi."
Meanwhile, Presidential spokesman Ernesto Abella confirmed that the fighters had taken over several government buildings in the city, and had torched others, including a church, a school and the city jail.
In comparison to the rest of the country, which is overwhelmingly Catholic, Mindanao is home to a sizable Muslim population.
The militants reportedly took over a medical center and replaced the Philippines flag with a black, ISIS-style banner.
In a statement, Armed Forces of the Philippines (AFP) spokesman Lt. Col. Jo-Ar Herrera said that Isnilon Hapilon, the leader of the Abu Sayyaf Group, which has pledged allegiance to ISIS, was among the armed men.
By Tuesday night, Abella said three government troops died in the fighting, and 12 were injured.
Even as reinforcements were expected in the troubled city, martial law was declared at about 10 p.m. Tuesday night.
A statement from the Armed Forces of the Philippines said, "Our operation is still ongoing in Marawi City and sporadic fighting is still continuing. The joint AFP-PNP team that is after Isnilon Hapilon and his cohorts is determined to finish him off."
Abella said residents were sheltering in their houses overnight.
Social media users posted photos from the city, showing residents attempting to evacuate the city on Wednesday morning.
Abella added martial law will be in effect on the Muslim-majority southern Philippines island for 60 days "to suppress lawless violence and rebellion and for public safety."
Under the 1987 constitution, the president has the ability to place the country under martial law.
However, the Congress has the ability to revoke the proclamation and the period should not last more than two months.
Duterte, however, hinted that martial law in the southern Philippines could last a year.
In a video posted on Facebook by Mocha Uson, the assistant secretary to the Presidential Communications Operation Office, Duterte said, "If it would take a year to do it, then we'll do it. If it's over within a month, then I'd be happy."