By Garba Mohammed and Farouk Umar
KADUNA/SOKOTO, Nigeria (Reuters) - Gunmen on motorbikes attacked the country house of Nigerian Vice President Namadi Sambo in Zaria in northern Kaduna state on Monday, but he was not in the building at the time, police said.
One civilian was killed in the attack, police added.
"The policemen on guard and the assailants were engaged in a gun battle around 1130 (0630 EDT), however, a cobbler was hit by a stray bullet and died instantly," police spokesman Balteh Abdulrazaq said.
Islamist sect Boko Haram are behind almost daily killings in the north of Nigeria in an insurgency against President Goodluck Jonathan's administration. The sect mostly targets authority and religious figures.
The sect wants to carve out an Islamic state within Africa's largest oil exporter, a country of more than 160 million people split roughly equally between Muslims and Christians.
Hundreds of miles northwest of Zaria in the remote city of Sokoto, suicide bombers targeted police stations on Monday.
"Two suicide bombers attacked two police formations in the state capital ... as a result three people died that includes the two bombers and a police officer," Muktar Bello, police spokesman in Sokoto, told Reuters.
A Briton and an Italian were killed by their captors in Sokoto in March during a failed rescue attempt.
Suspected members of Boko Haram killed five people and lost four of their members in a series of gun battles in Nigeria's second largest city Kano on Sunday.
Security experts believe Boko Haram has many cells operating independently from each other. The sect recruits from the millions of disillusioned youths in the impoverished north, who can be easily coerced into joining the insurgency.
(Additional reporting by Augustine Madu in Kano and Buhari Bello in Jos; Writing by Joe Brock, editing by Diana Abdallah)