The attack took place in the town of Dikera in Niger state, according to MP Jafaru Mohammed. It took place after Friday prayers had ended.
The shadowy militant group Lukawara is usually considered to be active in the northern parts of the country, and researchers believe the group has links to the ISSP terrorist movement, which is active in Niger, Burkina Faso and Mali in the Islamist insurgency that has been going on for almost two decades.
"Hundreds of supporters of the Lakuwara armed group attacked us," said Jibril Ahmad, who survived the attack.
A rival Islamist group, called Mahmuda, counterattacked and fighting broke out, according to witnesses.
There are no official figures on the death toll.
