Armored Personnel Carriers of the Philippine National Police arrive at the Resorts World Manila complex early Friday, June 2, 2017 in suburban Pasay city southeast of Manila, Philippines.

A gunman burst into a casino in the Philippines on Friday, firing shots and setting gaming tables alight, and at least 36 people were killed, most suffocating in thick smoke, in what officials believe was a botched robbery.

There was no evidence linking the attack at the Resorts World Manila entertainment complex to fighting between government troops and Islamist militants in the country's south, said Ernesto Abella, a spokesman for President Rodrigo Duterte.

"All indications point to a criminal act by an apparently emotionally disturbed individual," Abella told a media conference.

"Although the perpetrator gave warning shots, there apparently was no indication that he wanted to do harm or shoot anyone."

Police said the gunman killed himself soon after the attack, and they later announced they were looking for a second "person of interest" who was believed to be a Philippine national.

Most of the dead suffocated in the chaos as guests and staff tried to flee choking smoke at the complex after the attack began shortly after midnight (1600 GMT).

Oscar Albayalde, chief of the capital's police office, said those that died were in the casino's main gaming area.