Philippine police say the attacker was a tall, English-speaking white man with a mustache. They say he carried an assault rifle, and that he used gasoline to start a casino fire that caused clouds of smoke that left at least 36 people dead Friday morning in a sprawling entertainment complex in Manila.
But by Friday evening, police said they still didn't know the man's name, or why he launched his attack, only to flee to an adjoining hotel and kill himself.
Authorities say they suspect the man was trying to rob the casino at Resorts World Manila, a complex of hotels, restaurants, stores and a multi-floor gambling area. He stole more than $2 million worth of casino chips, though he apparently abandoned them in a toilet soon after.
"Either he lost in the casino and wanted to recoup his losses or he went totally nuts," Metropolitan Manila police chief Oscar Albayalde said.
The Islamic State, however, claimed responsibility in a statement Friday night. "Brother Abu al-Kheir al-Arkhabili was able to immerse among a gathering of Christian fighters in the Resorts World Manila in Manila where he carried out killing and hurting until he died as a martyr. About 100 Christians were killed or wounded," it said.
NBC News reports, however, that ISIS's claim remains quite questionable for a number of reasons, including contradictions made by the terror group. Police have also said this does not look like a terrorist attack.
Many in Manila feared after the attack began early Friday that it was linked to ongoing battles with Muslim militants aligned with the Islamic State group in the southern city of Marawi. The fighting has placed much of the country on edge and raised fears that the ISIS group was gaining a foothold.
But police told reporters that the man acted alone and didn't shoot anyone he encountered, pointing his gun upward when he fired some shots.
"He would have shot all the people gambling" if his goal was terrorism, national police chief Ronald dela Rosa said.
As the gunman left, he did exchange shots with a building guard, who managed to shoot him in the leg after being wounded, police and casino officials said.
Stephen Reilly, the Resort World's chief operating office, said "severe blood loss from the gunshot wound significantly slowed the assailant down and resulted in his holing up in a room where he took his own life."
Dela Rosa said security video showed the gunman earlier ignoring a guard who tried to question him at the complex's entrance. He then barged into the crowded casino with the gasoline and rifle after overcoming efforts by guards to stop him. He stuffed a backpack with gambling chips, fired his assault rifle at TV screens and set gambling tables on fire by pouring gasoline onto them from a 2-liter bottle he carried, dela Rosa said.
The gunman, whom dela Rosa described as "white, with a mustache," about 6 feet tall and English speaking, fled the gambling area and barged into a room on the 5th floor of Maxims Hotel, which is part of the Resorts World complex. He lay down on the bed, covered himself with a blanket, doused himself with gasoline and then set himself on fire, dela Rosa said. He carried no identity documents, police said.
Police were examining his car, which he left in a complex parking garage, authorities said.
The bag of high-value gambling chips — with an estimated worth of 113 million pesos, or more than $2 million — was found in a toilet.
The attack sent hundreds of people fleeing through the complex and into the night. A South Korean died of a possible heart attack suffered during the evacuation, the Foreign Ministry said. More than 70 people suffered mostly minor injuries in the stampede to escape.
Ronald Romualdo, a Resorts World maintenance worker, said he and his colleagues heard gunshots and saw people smashing windows on the second and third floors to escape.
"We took out a ladder to save them. We were able to save many of them," he said. "But one woman I was trying to save fell from the second floor. ... I could not carry her." He said the woman was not moving after she fell, but he didn't know what happened to her.
About 90 minutes after the attack began, Resorts World Manila said on its Facebook page that it was on lockdown following reports of gunfire and it was working to ensure the safety of guests and workers.
As news of the attack spread, President Donald Trump offered America's thoughts and prayers to the Philippines.
"It is really very sad as to what's going on throughout the world with terror," he said from the White House Rose Garden. Trump said he was "closely monitoring the situation."
Philippine President Rodrigo Duterte, however, made no mention of the attack in a speech he gave to soldiers Friday in the country's south.
The unrest in Marawi has sparked fears that militants might attack elsewhere to divert the focus of thousands of troops trying to quell the siege. But dela Rosa said, "We cannot attribute this to terrorism without concrete evidence."
Associated Press journalists Teresa Cerojano, Joeal Calupitan and Bullit Marquez contributed to this report.