COTABATO, Philippines (AFP) – – A powerful improvised bomb exploded in the troubled southern Philippine province of Maguindanao, killing a seven-year-old boy, police said Tuesday.

The bomb also wounded five people, including two teachers, in the explosion late Monday outside a town hall near a police station, provincial police chief Alex Lineses said in a statement.

No group has claimed responsibility for the attack and the motive was still being investigated, Lineses said.

Musiv Tan, an official at the local mayor’s office, said witnesses claimed suspects aboard a motorcycle had left the bomb wrapped in a black bag near a police outpost.

A provincial military spokesman, Colonel Benjamin Hao, said the incident could be related to a blood feud between a local mayor and his nephew who is a believed to be a commander of a Muslim separatist group operating in the area.

Vendetta killings and attacks between rival clans are common in Maguindanao, a province on the southern island of Mindanao where a powerful Muslim clan was accused of killing 57 people last year in the country’s worst massacre.