Maysun al-Hashimi's bodyguard was also gunned down in the attack. They were traveling in a car at the time of the ambush.
Tariq Al-Hashimi, a Sunni Arab, was appointed on April 22 in efforts to form a unity government. He is the head of the Iraqi Islamic Party.
The latest violence comes after one of his brothers was killed earlier this month.
(AP, Reuters, AFP)