"The suspected IED was placed at a terminal for motorcycles in front of the public market," Lt. Col. Junie Buenacosa, the police chief of the provincial capital of Insula, said, as quoted by the PNA news outlet.
The police chief added that a traffic police officer was among those injured by the explosion. He was hospitalised.
According to the media outlet, an unidentified perpetrator set off the device outside a market in the city.
Mindanao is home to a large portion of the Philippines' Muslim population.
Insulan has repeatedly been targeted by bombings over recent years. In 2018, two explosions killed five people and wounded 45 others. Moreover, in April, another blast targeted the same highway, where the market hit on Saturday is located, according to PNA.
The agency noted that a militant group linked to the Daesh* terrorist organisation had been blamed for the April bombing.
*Daesh (also known as ISIS/ISIL/IS) is a terrorist group banned in Russia
