It was the latest in a surge in militant attacks in the run-up to Iraq's crucial parliament elections on April 30.
Deputy police chief in the northern city of Kirkuk says the attack occurred late last night in Daqouq village.
Maj Gen Torhan Abdul-Rahman Youssef says the gunmen were disguised in military uniforms and told the guards at the polling center that they were there to do a search.
Youssef says the militants later shot to death the 10 guards.