Eight bodyguards of Qassim Mehawi, deputy head of the Communications Ministry, were also injured in the attack and were taken to the hospital, police officials said.
Government officials are frequent targets of the insurgents, who accuse them of collaborating with the Americans.
In other developments:
Wednesday marked the launch of the campaign for a Jan. 30 vote for a 275-member National Assembly. The start of election campaigning was subdued due to security fears.
In the northern city of Kirkuk, several thousand Arab residents rallied Thursday in front of the governor's office to demand that the elections be postponed.
The protesters said they were worried that a campaign to return displaced Kurds to the city, where Saddam Hussein's regime drove out many Kurds and replaced them with Arabs from other areas, would alter Kirkuk's ethnic mix.
On the final day of candidate registration on Wednesday, interim Prime Minister Ayad Allawi, a secular Shiite and Washington favorite, announced his 240-member list of candidates, pitting him against the slate embraced by Iraq's most influential Shiite cleric, Grand Ayatollah Ali al-Sistani. About 90 parties and political movements have applied to be represented on ballots.
Heading the al-Sistani-backed United Iraqi Alliance list is Abdel-Aziz al-Hakim, leader of the pro-Iranian Supreme Council for the Islamic Revolution and chief of its armed wing, the Iran-based Badr Brigade, during Saddam's rule.
With the threatened Sunni boycott, the lists submitted make Allawi and al-Hakim the leading contenders to take top jobs in Iraq's next government.
In the election, each faction will win a number of seats in the assembly proportional to the percentage of votes it gets nationwide — meaning the highest-listed candidates on each roster are most likely to be elected. The groups ending up strongest in the assembly will be in a powerful position — the body will elect a president and two deputies, who will nominate the prime minister. The assembly will also draw up a new constitution.
Shiites make up 60 percent of Iraq's 26 million population and are expected to dominate the polls.