Kirkuk, Iraq ? A suicide truck bombing followed by two smaller car bombs killed more than 80 people and wounded at least 180 Monday in what’s believed to be the deadliest attack in this northern city since the start of the war, police said.

The blasts in this city of deep tensions between Kurds and Arabs came as Sunni insurgents were believed to be moving north, fleeing a U.S. offensive around Baghdad and consolidating to carry out deadly bombings.

The massive explosion from the truck bomb around noon blasted a 30-foot-deep crater and damaged part of the roof of the headquarters of the Patriotic Union of Kurdistan, the party of President Jalal Talabani.

The main street outside the office was strewn with blackened husks of two dozen cars, and at least 10 shops were damaged, as well as part of the fence of the nearby Kirkuk Castle, a historic fortress that is one of the city’s most prominent landmarks.

The blast killed at least 80 people and wounded more than 183, according to police Brig. Burhan Tayeb Taha.

Twenty minutes later, a car bomb exploded about 700 yards away in the Haseer market, an outdoor bazaar frequented by Kurds, Maj. Gen. Jamal Tahir, the police chief, told The Associated Press. The market was largely empty after the first attack, and the explosion caused several injuries.

Hours later, a car bomb exploded in the Domiz region of southern Kirkuk, killing a police officer and wounding six other policemen, Tahir said.

Oil-rich Kirkuk, 180 miles north of Baghdad, is a center of tensions between Arabs and Kurds, who want to include the area in the autonomous Kurdish region of the north.

Violence in the city, though frequent, tends to be on a smaller scale of shootings, roadside bombs and kidnap-slayings.