Two crewmen of a US Apache helicopter have been killed in a crash north of Baghdad, the US military says.
The US said the helicopter was on combat patrol on Monday near the town of Mishahda. Witnesses said it was hit in a rocket attack.
Also on Monday a bomb attack in a town north-east of Baghdad killed five Iraqi policeman and a child, officials said.
The US military has warned violence may worsen after the results of December's elections are confirmed this week.
On Monday, election officials threw out ballot boxes from 227 of the 32,000 voting centres because of fraud, but analysts say this is unlikely to affect the overall result.
The US helicopter crash was the third in 10 days in Iraq.
The US military said it was "premature to determine the cause of the crash".
But local witnesses said the Apache came under missile fire near Mishahda.
Two little-known Iraqi militant groups both said they carried out the attack, but their claims cannot be verified.
The Mujahideen Army posted a website video of a helicopter being shot down. Arab television channels later broadcast the footage, showing a surface-to-air missile hitting an aircraft.
The Salaheddin al-Ayubi Brigades issued an internet statement saying one of its brigades "shot down an Apache helicopter in the Mishahda area with missiles".
The incident follows the crash on Friday of a US reconnaissance helicopter near the northern city of Mosul, which killed both crew - an attack blamed on insurgents.
Earlier this month, a US Black Hawk helicopter crashed near the rebel stronghold of Talafar in northern Iraq, killing eight passengers and four crew members on board.
Monday's bomb attack took place in Muqdadiyah, 100km (60 miles) north-east of Baghdad, police said.
The election commission said only 58 poll complaints were serious
In addition to the five policemen and child killed, 18 others were wounded, officials said.
They said the blast occurred as police reinforcements arrived to deal with a fire fight with militants.
A police officer and a civilian also died in two separate shootings in Baghdad on Monday, police said.
The violence comes as Iraq prepares for the confirmation of the 15 December parliamentary elections later this week.
The election commission said on Monday less than 1% of ballot boxes would be declared void because of fraud.
Preliminary results suggest a strong lead for the Shia Muslim bloc but not enough for a majority without the aid of Sunni or Kurdish groups.