Baghdad ? A car bomb exploded near a Kurdish party’s office Tuesday in Mosul, killing at least three Iraqi soldiers as tensions rose in volatile areas north of Baghdad ahead of pivotal elections.

Friction between Kurds and Sunni Arabs, as well as Sunnis and Shiites, has made northern Iraq a key battleground with just four days to go before the vote. Iraqis will choose ruling councils Saturday in most of the country’s provinces.

The blast in Mosul, 225 miles northwest of Baghdad, occurred near the offices of the Kurdish Democratic Party, or KDP, which is headed by Kurdish leader Massoud Barzani.

Iraqi security forces became suspicious of the vehicle, which blew up as a team approached to inspect it, an army officer said.