The blast in Indonesia's restive eastern Papua region startled locals with a thunderous boom a day earlier, emitting a ball of flame, followed by a thick smoke column, according to footage broadcast on Kompas TV.
Nine homes were destroyed.
"The source of the explosion is strongly suspected to have been a bomb or mortar left over from World War II," Papua police spokesman Cahyo Sukarnito told AFP.
Three people are still recorded as missing, but Cahyo said several body parts have yet to be identified.
At least 19 people were treated for minor injuries, he added.
