A police station in the northern Nigerian city of Maiduguri has been destroyed in an attack blamed on the Boko Haram Islamic sect.
One policeman was injured by gunmen who shot at the entrance before an explosion inside injured another policeman and woman.
At least 18 people, mostly police officers, have been killed in the city in the past two months.
Clashes between Boko Haram and the police in July 2009 left hundreds dead.
The BBC's Bilkisu Babangida in Maiduguri says the attack follows the killings on Saturday of an Islamic scholar, his follower and a policeman in separate attack.
The scholar was believed to have been preaching against the sect, which is opposed to Western education and accuses Nigeria's government of being corrupted by Western ideas.
Our correspondent says the attack on Monday night happened at about 2130 local time.
Police say a locally made Molotov cocktail exploded inside the police station, which is in the Gamboru suburb, near the former headquarters of Boko Haram.
Most of those killed in the recent assassinations have been shot by people riding motorbikes.
In a bid to reduce the killings, motorbikes have been banned at night but the shooting have continued.
Hundreds of people suspected of being Boko Haram members escaped from prison in September after gunmen attacked the jail where they were being held in the city.
Last year's violence started when Boko Haram members attacked a police station in Maiduguri before clashes spread to neighbouring areas.
Most of those who died were supporters of the sect, which is also known locally as the Taliban and wants to see Islamic law imposed across Nigeria.
The sect's leader, Mohammed Yusuf, was among those killed, apparently after he was handed over alive to the police.