As an ISIS-inspired insurgency rages in the country’s south, Philippines’ authorities are assuring the public that an attack on a luxury resort in Manila that left more than three dozen dead wasn’t an act of terrorism, but was, in fact, a robbery.

A gunman armed with a "baby armalite" rifle burst into the Resorts World Manila casino on Friday and started firing off shots and setting gaming tables alight on Friday, authorities said, before making his way to the back of the casino where he stole several million dollars' worth of gambling chips. Most of the dead suffocated on the thick smoke, according to Reuters. However, despite authorities assurances, the high death toll and brazen nature of the attack suggest that terrorism may have been the underlying motivation. US terrorism monitor the Site Intelligence Group said an Islamic State-linked Filipino operative claimed “lone wolf soldiers” of ISIS were responsible for the attack, according to the Guardian.

"All indications point to a criminal act by an apparently emotionally disturbed individual," Ernesto Abella, a spokesman for Duterte, told a news conference. "Although the perpetrator gave warning shots, there apparently was no indication that he wanted to do harm or shoot anyone."

The gunman killed himself in his hotel room after being shot and wounded by resort security, police and Resorts World management said. A second "person of interest" who was in the casino at the time was cooperating with the investigation, Reuters reported.

The national police chief, Ronald dela Rosa, said security footage showed the gunman going straight to the casino after ignoring a guard who tried to question him at the complex’s entrance. He stuffed a backpack with gambling chips, fired an assault rifle at TV screens and set gambling tables on fire by pouring gasoline on to them from a two-liter bottle, Dela Rosa said, according to The Guardian.

It was not clear how he smuggled the gasoline and rifle into the crowded casino. The bag of high-value gambling chips was found in a toilet. Dela Rosa described the gunman as white, about 6 ft. tall and English-speaking.

However, there’s no evidence linking the attack to fighting a fierce 10-day battle that has been raging in the city of Marawi, about 500 miles south of Manila. Last week, the Philippine president Rodrigo Duterte imposed martial law across the southern region of Mindanao, arguing it was necessary to root out the insurgents, Reuters reported.

In Marawi, the army has deployed helicopter gunships and artillery fire to try to dislodge the gunmen, but they have held a large section of the city, according to the Guardian. Security forces have been deployed to other cities in Mindanao province, concerned that the militants may attempt to launch attacks outside Marawi.

The clashes started after security forces tried to capture Isnilon Hapilon, an ISIS-endorsed Islamist militant leader who is the subject of a $5 million reward offered by the FBI.