Eight Iraqi soldiers were killed when a house they were preparing to raid blew up in Iraq's northern Diyala province.
The early morning explosion happened in Sadiya, 100km (60 miles) north-east of Diyala's capital Baquba, police said.
It comes a day after six people were killed in attacks across the country, including two members of an anti-insurgent group and two policemen.
Violence has spiked in recent weeks, ahead of a major withdrawal of US troops due to be completed this month.
Iraq is also grappling with a five-month-long political impasse after a March parliamentary poll failed to produce a clear winner.
Iraqi officials say a gunman opened fire from a house near an Iraqi army checkpoint in Sadiya at around 0500 local time (0200 GMT).
When soldiers surrounded the house, it blew up, killing eight of them.
Maj Hussam Karim told the AFP news agency that the army had imposed a curfew in the area and was searching for the armed men, who were thought to have escaped through a back door.
Meanwhile, in the capital Baghdad, the head of a maternity hospital was shot dead by gunmen who tied up her husband before killing her.
The violence comes as Iraq observes the Islamic fasting month of Ramadan, which has coincided with a spike in insurgent activity in previous years.
Already this month, more than 100 people have been killed in violent attacks across the country. July was the country's deadliest month since 2008.
It has fuelled concerns about security as the US prepares to end all combat operations and hand over security to Iraqi forces by the end of the month.
All US forces are set to leave Iraq by the end of 2011.