Gunmen attacked a police station in Nigeria's flashpoint city of Kano at dawn on Monday, setting off a gun battle with police, residents said.

It is the second time in three days that the Mandawari police station has come under attack in Kano, the country's second biggest city and the scene of one of the deadliest attacks blamed on the Islamist sect Boko Haram.

"It was crazy. These guys came on motorcycles and opened fire on the police station but they met tough resistance from the police, and it lasted around 20 minutes," Jamilu Muhammad, who lives across the police station, told AFP.