Wasiu Abiodun, spokesperson for the police in Niger, told Xinhua by telephone that an unspecified number of people were abducted following the attack in Dekara, a community in Borgu Local Government Area, on Friday.
The gunmen surrounded the mosque and led the worshippers away through a bush path, Abiodun said.
He said security operatives had launched a rescue operation, but their efforts were being hampered by a collapsed bridge linking the main town with the affected community, as well as difficult terrain and poor road conditions in the area.
Niger State has witnessed repeated incidents of violent attacks in recent years, including banditry and kidnapping.