Two blasts jolted separate locations in Indonesia's restive Central Sulawesi province, but caused no casualties, police said on Thursday.
In Poso, a strong blast came from an empty plot some 200 metres (yards) from a military barracks late on Wednesday night, Central Sulawesi deputy police chief I Nyoman Sindra said in Palu.
"Last night's blast in Poso is still under police investigation and it cannot yet be ascertained whether it was due to a bomb or a strong firecracker," Sindra said.
Another blast was heard coming from a cacao plantation in the Dolo area just south of Palu, the provincial capital, about two hours later, Sindra said.
A police team was combing the plantation to find the blast's site and what had caused it, he added.
A resident, Sumardin, told reporters that the explosion sparked panic among people attending a small feast at a home just outside the plantation.
Unrest pitting Muslims and Christians in Central Sulawesi, especially in Poso town and the surrounding district of the same name, flared dramatically during 2000 and 2001, leading to about 1,000 deaths.
Intermittent violence and tensions have continued since.
Poso came under the international spotlight in 2005 when Islamic militants beheaded three teenage Christian schoolgirls.