Kano, Nigeria - Muslim radicals killed at least 13 police in the northern Nigerian city of Kano on Tuesday to avenge the assassination of a hardline cleric four days earlier, police and witnesses said.
The attackers, from an extreme Islamic sect, burned down a police station in the Panshekara district, wounding two officers, and then ambushed and killed 13 police who came to investigate, residents said. .
Earlier reports said the wife of one of the officers was killed.
"I saw four of them. They were standing at the crossroads, heavily armed. They tied their heads with white cloths so they could not be recognised," said Theophilus Michael, 37, a factory worker.
Last Friday, Saudi-educated cleric Sheikh Jafar Adam was shot five times at close range while praying at the Dorayi Central Mosque in Kano. He died before reaching hospital.
Authorities had previously blamed the attack on a dispute between rival Islamic sects.
"They said they had nothing against civilians. They just wanted to attack the federal government, the police, for the killing of the sheik," said Baba Ow Jafet, a 28-year-old resident of Panshekara.
A police officer said the attackers were looking for anyone in uniform.
Kano has seen several bouts of ethnic and religious bloodshed over the last few years, and tensions are running high in the city of 6 million because of flawed state elections held on Saturday and a presidential vote on April 21.
It was not clear if the latest violence was connected to the elections.
The attack was the second on a police station in northern Nigeria's biggest city in a week. Attackers killed a divisional police officer in the Sharada district last week but the motive for that incident was not clear.
Kano is one of 12 northern Nigerian states which introduced sharia law in 2000. The move by state governors alienated Christian minorities and sparked violence.
Southern Nigeria is predominantly Christian.