Iraqi police say a U.S. military strike killed eight people, including two children, north of Baghdad.
The police officials say the helicopter strike targeted at least one vehicle near the town of Baiji Wednesday.
The U.S. military confirmed there was an incident involving U.S. forces and said an investigation was underway.
Earlier, the U.S. military said American soldiers shot dead 11 Iranian-backed Shi'ite insurgents in eastern Baghdad during security operations on Wednesday.
However, Iraqi police have said not all of the dead were insurgents, and an Iraqi television station says one of its cameramen was killed in the crossfire as he headed home.
The body of a second journalist was found Thursday near the Diyala provincial capital of Baqouba.
Police said Haidar Hashem al-Huessein had been kidnapped earlier this week.
Meanwhile, Baghdad's Sadr City remained calm Wednesday, a day after 10,000 Iraqi security personnel entered the Shi'ite militia stronghold to assert government control. Their deployment is part of a truce with militiamen loyal to radical cleric Moqtada al-Sadr.
In another development, Major General Mark Hertling, the top U.S. commander in northern Iraq, said a security crackdown by Iraqi and coalition forces has sharply reduced violence in the Mosul region.
He said daily attacks in Mosul have fallen from an average of 40 to six over the past week. The U.S. commander also said authorities have detained 1,200 suspected al-Qaida fighters during the period.
Some information for this report was provided by AFP and AP.