HAIKOU -- An explosion killed four people and injured another on Monday in south China's Hainan Province in what seems to have been an attempt to strip fireworks to make explosives for use in fishing.

Han Jinghua, deputy head of the provincial public security bureau, arrived in Baisha, a Li ethnic autonomous county, to oversee the investigation of the accident on Monday afternoon.

He urged local authorities to make door-to-door checks in order to confiscate such illegal explosives made from powder contained in fireworks, as the method has become catching on in the region.

Chen Liqiang, a publicity official in Baisha, said among the dead was a villager surnamed Fu and his four-year-old daughter. Fu is thought to have hired three others to make the explosives.

The police chief has asked local authorities to erect warning signs near rivers and reservoirs forbidding the use of explosives for fishing, and to prevent illegally homemade explosives from entering the market.