Philippine officials are trying to determine who set off a deadly explosion in a marketplace crowded with shoppers.
Sunday's blast in the southern city of General Santos killed at least 13 people and injured dozens more. Police said the blast may have been caused by a homemade bomb.
No one has claimed responsibility for the explosion, and officials initially offered competing explanations.
Muslim separatists were blamed for a previous deadly explosion in General Santos, and officials say the groups continue to operate there.
Some information for this story provided by AFP and Reuters.
