A suicide car bomber killed at least five people in Nigeria on Friday outside police headquarters in the north-eastern city of Maiduguri.
The vehicle was driven into the entrance of the building.
Police stations are a favourite target for the Boko Haram group which first came to prominence in 2009. The name means "No to Western education".
In January, attacks on a number of police stations in the city of Kano killed 186 people, most of them civilians.
The BBC reports Boko Haram carried out a suicide bomb attack last Sunday on a church in Bauchi city in which 12 people were killed.