Philippine police say 15 vendors, including four children, have been killed in a pre-dawn fire that hit a public market in the country's south.

Senior Superintendent Angelito Casimiro says 13 other vendors have been injured in the three-hour blaze.

He says it was apparently started when sparks from low-slung electric post cables set fire to sidewalk stall umbrellas then ignited stacks of used clothing being sold at the Zamboanga city market.

Police investigator Rafael Salcedo says the victims were clothes vendors who slept at their stalls, including at least four children, so they could be up early for the weekend market that usually draws sizable crowds.