A car bomb exploded in the centre of the Iraqi Kurdish capital Arbil on Wednesday, killing several people, local television reported.
Footage from the scene showed several charred vehicles and what appeared to be a blood stain on the cobbles outside the governor's office.
A witness at the scene said two police and two civilians had been killed.
Islamic State militants who overran swathes of northern Iraq this summer have repeatedly threatened to launch attacks against Kurdistan, but the region has so far largely managed to insulate itself from the violence.
The last major attack in Arbil was more than one year ago, when militants launched a coordinated suicide and car bomb attack on the headquarters of the security services. Another blast took place in August, but there were no casualties.