Fears have been expressed for the safety of public facilities in Manila after a lone gunman was able to enter an upscale casino and hotel complex with an M4 carbine and gasoline, firing shots and setting fire to gaming tables before immolating himself.

Thirty-six bodies were found in the wake of the brazen attack on Resorts World Manila, which took place in the early hours of Friday morning. The Metropolitan Manila police chief told AP that they had suffocated from smoke set off by the gunman.

According to a statement from Resorts World, 30 people were brought by its security team to hospital for medical attention. The Manila Bulletin reported that 54 people were hurt when they jumped for safety.

ISIS claimed responsibility for the attack, AP reports, and there are concerns that ISIS-affiliated militants, currently under siege in the southern city of Marawi, have been planning diversionary attacks elsewhere in the country. However, police say there is no immediate evidence of a terrorist link.

Richard Heydarian, assistant professor of political science at De La Salle University in Manila, told TIME via email that “Regardless of the affiliation and identity of the assailants, whether tied to ISIS or just a criminal [act], the attack took place in one of the poshest and safest areas in the country,” and would “add to a long list of negative perceptions about the Philippines,” which is currently in the throes of a brutal, globally condemned war on drugs.

The unidentified attacker, described by police as a Caucasian foreigner, caused mayhem in the complex of hotels, casinos, shops and restaurants in the upscale Newport City district when he rampaged through a second floor gaming hall.

Newport City resident Roxanne Lu told TIME that she was advised by security officers to stay in her apartment and spent the night listening to sirens. “We didn’t know if there were bombs planted or armed men spread out,” she said, adding that she was first alerted to the trouble when a worried friend called her saying that he could see smoke billowing from Newport City from his apartment 7 kilometers away.

Noreen Gonzales, 21, said she finished eating a meal at the complex just minutes before the attack, and thought it had come under assault from terrorists, describing the panic as terrifying. “We thought it’s an ISIS attack because what’s happening in Mindanao,” she told TIME.

She told TIME that the security failure that allowed a gunman into the complex worried her, because she worked as a check-in clerk at Manila’s Ninoy Aquino International Airport, just opposite Resort World, and feared that the airport could be “really an easy target for the Manila area.”

It remains uncertain how the attacker was able to smuggle an assault rifle and inflammable liquids into the complex. Patrons routinely undergo bag inspections and must pass through metal detectors at many malls and hotels in the Philippines, where firearms are readily available and where an Islamist insurgency has seen the declaration of marital law on the archipelago’s second largest island, Mindanao.

“The Philippine security forces in posh areas are well equipped, so this could be intelligence failure and a shortcoming on the part of the casino’s security structure too,” Heydarian said.

He added: “The pressure is on the Duterte administration to avoid public panic, double down on its anti-crime bona fides, and reassure investors that the

Philippines is a safe place to go to. It will be an uphill battle.”

—With reporting by Kevin Lui / Hong Kong

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Write to Joseph Hincks at joseph.hincks@time.com.