The attack occurred as local Iraqi police were gathered near the main gate of the station in Jalula with Kurdish troops who came to the area as part of a security crackdown, police said.
The eight killed included four Iraqi police, two Kurdish troops and two civilians, police said.
Ahmed Khatab, a doctor at the local hospital, confirmed the death toll and said eight of the 30 wounded were in critical condition.
Jalula, 110 kilometers (68 miles) northeast of Baghdad, is a religiously mixed city in the Diyala province, a former al-Qaida in Iraq stronghold that has seen a dramatic drop in violence after an influx of U.S.-led forces but continues to see dramatic attacks.
U.S. commanders have warned extremists in Iraq still pose a serious threat.