Police said at least 50 people were injured trying to flee the casino complex.
Around dawn, the body of the suspected gunman was found in a hotel room in the complex, which is close to Ninoy Aquino International Airport and an air force base.
Dozens of people were injured as panicked guests rushed to get out the building, according to Resorts Chief Operating Officer Stephen Reilly. He said the others sustained only minor injuries.
The police chief confirmed his original statement to the AP that there is "no concrete evidence that the attack was terrorism" - despite President Trump's opening remarks while announcing the US withdrawal from the Paris accord on climate change.
People ran screaming out of Resorts World Manila, which is across a road from the Philippines' worldwide airport, after the man fired what police chief Ronald dela Rosa said was an M4 assault rifle and set fire to a gambling table around midnight. "But he did not hurt anyone".
Police said earlier the man's motive was likely robbery and that the incident was not terror-related.
Mr dela Rosa said security footage showed the gunman ignoring a guard who tried to question him at the entrance to the complex. "We can not attribute this to terrorism", Dela Rosa said.
The incident unfolded in the early hours of Friday morning local time when the armed suspect forced his way into the Resorts World Manila casino, shot at gambling machines and set tables on fire.
It was not clear how the gunman smuggled gasoline and an assault rifle into the crowded casino or what prompted dela Rosa to cast doubt on terrorism so quickly.
"I heard many, many gunshots", Julio Silva, a casino player who managed to dash out of the mall complex amid the gunfire, told DZMM radio network.
Shortly after the incident began, the US State Department warned citizens to avoid the area.
A bag of gambling chips worth 113 million pesos (£176,500) was found in a toilet.
"We have been informed of several casualties, the number and identities of whom have yet to be determined", it said in a statement.
Windows were smashed on the second floor of the complex just before daylight broke, but it was unclear why and by almost 6:00 am police did not report any breakthrough in the hunt for the gunman.
In addition to the 36 found dead in the casino, the gunman was later found dead and a South Korea victim died in the evacuation. "I am very anxious as a parent, I need to find her", he said.
Speaking in the White House Rose Garden, Trump said he is "closely monitoring the situation" and will continue to provide updates.
As news of the attack had spread, President Donald Trump offered the thoughts and prayers of the American people to the Philippines. According to SITE, the message says the attacker meant to burn the casino because the activities inside were haram, or forbidden by Islam.
"We are still investigating if he has accomplice in committing the crime but initial reports and evidence point that the suspect was alone", Apolinario said.