An armed gang on motorbikes killed at least 30 people in attacks on two villages in Katsina state, police said on Saturday.
Twenty-one people were burnt to death and nine villagers were shot dead on Friday evening in the villages of Dankar and Tsauwa as the assailants made off with food and livestock, the police said.
Hundreds of people have been killed in the northwest of Nigeria since last year, in attacks the government attributes to bandits - a loose term for gangs of outlaws carrying out robberies and kidnappings.
Police commissioner Sanusi Buba confirmed the death toll and said that police and military teams had been deployed to the village, adding that an investigation is under way.
Security experts say Nigeria can ill afford more instability as it is already struggling to contain Islamist insurgencies in the northeast, conflict in central states and militant groups in the Niger Delta to the southeast.
The death toll from violence continues to rise in Nigeria, along with incidents of kidnapping and robbery.
Suspected Boko Haram Islamists killed at least 30 people on the night of Feb. 9 in Borno state.