PHILIPPINES- Gunfire and explosions have been heard at the Resorts World Manila in the Philippines, CNN Philippines reported.

The incident in Manila comes as the entire country is on high alert following the attack by the Maute Group in the southern city of Marawi in Mindanao, which left over 100 people dead, including many civilians.

Resorts World Manila said on social media it was in lockdown and the local fire department said a blaze was burning on the second floor of the building.

But the resort complex then said on Twitter that police operations were still "ongoing" and that they did not have "official information as to the identity or affiliation of the persons responsible for the attack".

Dela Rosa said the man, who appeared to be acting alone, walked into one of the gambling rooms and fired the rifle at a large television screen, then poured gasoline onto a gambling table and set it alight.

"There were other gunmen because we can hear gunshots elsewhere", he told Manila radio station DZMM.

The gunman did not shoot anyone but disappeared into the chaos of smoke and running people, leading to a manhunt throughout the casino, hotel and shopping complex that ended just after dawn.

Dela Rosa said he could not say if it was terrorist attack, but emphasised the gunman did not shoot anyone and there had been no reports of hostages being taken. "We were able to save many of them", he said. "We ask for your prayers during these hard times".

President Rodrigo Duterte declared martial law on the southern island of Mindanao last week.

Witnesses reported seeing injured people, including a SWAT officer who rushed to the scene and was reportedly fired upon. People have been taken away in ambulances.

"But it is really very sad as to what is going on throughout the world with terror". Trump said he was "closely monitoring the situation" and would continue to provide updates.

Within hours of the first gunshot, the terrorist group Islamic State in Iraq and Syria (ISIS) claimed responsibility for the attack, according to the SITE Intelligence Group, which monitors terrorist organizations.

Philippine police have not given details about the incident but have begun cordoning off the area near the Ninoy Aquino International Airport.