Iraqi authorities have imposed a ban on vehicles in the city of Baquba, north of Baghdad, in an effort to curb growing violence.
Friday's one-day curfew follows a series of suicide bombings and other attacks in Baquba, the capital of volatile Diyala province.
Also today, the U.S. military says it had killed two terrorists and detained 12 people during two operations in central and northern Iraq on Thursday.
A military statement says one of the detainees is an alleged leader of the terrorist group Ansar al-Sunna, which is linked to al-Qaida. It says another is believed to be involved in an al-Qaida in Iraq media cell.
The military said on Thursday that two American soldiers were killed and a third was wounded in a small arms action in Diyala.
Overall violence in Iraq has declined in recent months.
Some information for this report was provided by AFP, AP and Reuters.