The guerrillas arrived in the village of Gogone on foot and opened fire indiscriminately on residents, the sources said, adding that Niger troops had pursued them.
Niger's Diffa region has suffered dozens of cross-border strikes this year by the militant group whose stronghold in northeast Nigeria lies just a few kilometres away.
A state of emergency has been declared there in a bid to boost security.
But the attackers often manage to flee across the River Komadougou, marking the border with Nigeria.
Central African leaders in regional bloc CEEAC said on Wednesday at a summit that they were raising 50 billion CFA Francs ($80 million) to help Nigeria's neighbours fight the militant group.
An 8,700-strong regional task force with troops from Chad, Niger, Benin, Nigeria and Cameroon is operational but has yet to begin joint military strikes against the group.