At least two people were killed when a car exploded at a police station in Potiskum, northeast Nigeria, an officer told AFP.
The blast at the facility attached to the Potiskum Area Command at about 3:30 pm (1430 GMT) involved a driver and vehicle which had earlier raised suspicions at a checkpoint outside the city.
"It was while they were at the gates of the police station undergoing security checks that the car exploded," said the officer, who asked not to be identified.
"The policeman and the driver have been confirmed dead but details of other casualties are not clear yet."