The mayor in the town of Tuz Khormato says the attack happened around noon today.
Shalal Abdoul says a suicide bomber first drove his explosive-laden truck into a checkpoint leading up to the offices of the Patriotic Union of Kurdistan and the nearby Kurdistan Communist Party.
He says as people rushed to the site of the explosion, another truck bomb exploded, presumably detonated by remote control.
It was the second double bombing at Kurdish offices in as many days. Yesterday, a suicide bomber, followed by a car bomb explosion targeted PUK offices in Jalula in the ethnically mixed Diyala province.