Gunmen apparently targeting political candidates staged attacks around Iraq, leaving at least three people dead.
The shootings came as Iraqi forces began imposing a full-scale security clampdown in advance of voting for provincial council seats.
The level of violence around Iraq dropped significantly lower than in past years.
But Saturday's election was seen as an important test of Iraqi self-reliance and competence as the U.S. military begins to turn over more authorities to local forces.
Security measures taking effect Friday include closing Iraq's international borders, ordering traffic bans across Baghdad and major cities and halting air traffic.
Hundreds of women, including teachers and civic workers, have been recruited to help search women voters after a rise in female suicide bombers last year.