A man wearing an Iraqi army uniform has shot dead two US soldiers and injured three others in the northern city of Mosul, US military officials say.
Reports said the man, who was killed after the attack, opened fire on a group of soldiers at a combat outpost south of the city.
Saturday's casualties bring the US death toll in Iraq up to 20 for the month of April, the highest so far this year.
"We have reports of a small-arms fire attack in Hamam al-Alil, 20km south of Mosul," Major Derrick Cheng, a spokesman for the US military in Mosul and surrounding Ninawa province, said.
"According to initial reports, an individual dressed in an Iraqi army uniform fired on the coalition forces and was killed in the incident."
Witness accounts
A police officer in Mosul identified the assailant as Hassan al-Dulaimi, a soldier who also served as the imam of a mosque at an Iraqi army training centre south of Mosul, the capital of Ninawa.
He said the American soldiers were doing exercises in the training centre's yard at the time of the attack. He said he had no knowledge about the fate of the assailant.
Saad Ali al-Jubouri, mayor of Hammam al-Alil, said he saw US helicopters hovering over the area and that the roads leading to the training centre had been sealed off.
US troops could stay in Mosul beyond a June 30 deadline for withdrawing from Iraqi cities if Baghdad requests it, according to a Status of Forces Agreement (Sofa) concluded between the two states in November.
"We really look at trends, we don't look at single events, because whatever we do for a strategy is a months-long strategy," Major General David Perkins said on Friday.
He admitted, however, that US commanders were negotiating with their Iraqi counterparts over Mosul and that the question of whether US troops would remain there past the June 30 deadline was "undecided."
Past attacks
An Iraqi soldier went on the rampage last November at a joint security station in Mosul, shooting dead two US soldiers and wounding six.
The US military blamed the attack on al-Qaeda in Iraq.
In December 2007, an Iraqi soldier opened fire on US troops during a joint patrol in Mosul, killing two and wounding three.
In all, at least 4,283 members of the US military have died in the Iraq war since it began in March 2003, according to an AFP count based on an independent website.
Civilian deaths in Iraq in April were also higher than previous months following a series of bombings that killed more than 200 people.
At least 355 Iraqi civilians and Iraqi security forces were killed in violence in April, according to a monthly death toll issued by various Iraqi government ministries.
There are currently about 142,000 US troops stationed in Iraq.
PHOTO CAPTION
US soldiers patrol Mosul in 2008.
Al-Jazeera