A police officer has been killed by an explosion at police headquarters in the central Bosnian town of Bugojno.
"One policeman died of injuries, while six others were wounded, one of them seriously," a police official told AFP news agency.
"An unidentified explosive device went off during the morning shift at 0300 GMT when about 25 policemen were in the building," another local police officer told Reuters by telephone on Sunday.
He said that it was unclear whether the device, which also caused serious damage to nearby buildings and vehicles, had been planted or thrown at the police station.
"Such terrorist attacks represent a threat to the society and we have to energetically stem this evil, which is threatening the lives of our people," Sadik Ahmetovic, Bosnia's security minister, told state television.
Police said they have detained five suspects but did gave no information about the possible motives behind the attack.
FTV, Bosnia's national braodcaster, said the explosion caused "serious damage" to surrounding buildings as well as to the station itself.
It was still unclear what has caused the blast, FTV said, describing it only as a "very powerful destructive device" without giving further details.