Chief Superintendent Manuel Gaerlan, the director of Region 11 of the Philippine National Police, told CNN Philippines that 10 people had died at the scene, and two had died after being taken to the Southern Philippines Medical Center after the explosion on Friday.
He said a police and armed forces had been called in to secure the region.
He asked the public to be vigilant, adding that the government was on the watch "in case there are other attacks."
He said Philippines President Rodrigo Duterte, whose hometown is Davao City, was heading to the explosion site. The blast occurred at a busy night market known to attract thousands, on the southern Philippine island of Mindanao.
Paolo Duterte, Davao City's vice mayor and the President's son, told CNN Philippines that 60 people had been injured in the blast.
Authorities were still trying to confirm the cause of the explosion, he said. While the city was not on lockdown, there was an alcohol ban in place, and officials had asked people in the area to return to their homes.
