Gunmen attacked a convoy carrying delegates from the Arab League in western Baghdad on Monday, killing three police escorts but leaving officials mostly unscathed, the Iraqi police said.
The convoy of six to eight vehicles came under attack as it was travelling to meet representatives of the Muslim Clerics' Association, a Sunni Muslim group, for a Ramazan meal after sundown, the police and government sources said.
Gunmen opened fire as the convoy travelled past the Um al-Qora mosque, a large Sunni mosque in the west of the capital where the Muslim Clerics' Association is based.
Delegates from the Arab League, which groups 22 governments from across the Arab world, are in Baghdad to help oversee Saturday's referendum on a new constitution and to plan an upcoming visit by the its secretary-general.
Four police were also wounded in the attack and clashes that followed, the police sources said.
"As they were driving to the Iftar (Ramazan meal), gunmen hiding at the side of the road attacked them," said Saad al-Hayani, one of Iraq's deputy foreign ministers, who said he had been in touch with members of the Arab League delegation.
"They hit the police but all the diplomats are okay and are now with the Muslim Clerics' Association at the mosque."
He said one female member of the League delegation was slightly wounded by flying glass.
US troops arrived in the area shortly after the initial attack and were also fired upon, a policeman at the scene said.
At least two police vehicles overturned during the assault, which Hayani said appeared to have been carefully planned.
Earlier on Monday the delegates met with members of Iraq's government as part of talks to try to bring the Sunni Arab minority, which broadly opposes the constitution, on board before the referendum vote.