BAGHDAD, Iraq -- A pair of car bombings killed a U.S. soldier and 12 Iraqis yesterday and gunmen assassinated a senior Education Ministry official. The attacks continued a wave of violence against the U.S. occupation and Iraqis who cooperate with it as the June 30 transfer of power approaches.

Three rockets were fired into the heavily guarded compound where U.S. authorities live and work in downtown Baghdad. A senior U.S. military official said that only one of the rockets detonated, causing minor damage and no deaths or injuries. But the blast resonated through the city during morning rush hour.

About 15 vehicles rigged with explosives, some driven by suicide bombers, have been sent against U.S. occupation and Iraqi government targets so far this month, U.S. military officers said, meaning an average of at least one car bombing a day somewhere in Iraq.

The bombings were among a variety of violent engagements, occurring at the rate of 35 to 40 a day, in a campaign designed to demonstrate a lack of U.S. and government control in the days leading to restoration of Iraqi sovereignty June 30, the officers said.

As the attacks persisted in Baghdad yesterday, a senior spokesman for the insurgent Shiite Muslim cleric Muqtada al-Sadr said in Najaf that al-Sadr intends to "found a party to participate in political events." The spokesman, Qais Khazali, did not say whether al-Sadr also intends to disband his militia, the Mahdi Army, and abandon his military resistance to the U.S. occupation.

The suggestion of a political organization was in line with intense efforts by Shiite religious and political figures to persuade the young cleric to end his military challenge and turn instead to politics.

Despite a declared U.S. determination to force al-Sadr to stand trial on charges that he conspired in a fellow cleric's murder, these Iraqi Shiite leaders repeatedly have said that the solution to the al-Sadr crisis is to draw him into the political process and confrontation can lead only to more bloodshed.

The first car bombing, which took place in the eastern part of the capital as Iraqis drove to work in a morning traffic jam, killed four policemen and eight civilians, the U.S. military said.

Witnesses told reporters that an Iraqi police patrol tried to stop the vehicle as it sped toward Camp Cuervo, but it crossed the median and detonated in a suicide attack, demolishing the police car.

The second bombing, later in the day near the northern suburb of Taji, killed one U.S. soldier and wounded two, spokesmen reported.

The assassinated Education Ministry official, Kamal Jarrah, 63, was responsible for cultural relations with foreign countries and the United Nations. Gunmen shot him as he left for work from his home in the Ghazaliya district, police said.

Jarrah was the second high-ranking government professional to be killed by gunfire in the past two days. Assassins killed Deputy Foreign Minister Bassam Salih Kubba, a career diplomat, Saturday as he drove away from his home on the way to work.

The killings appear to be aimed at frightening away Iraqis who take part in the U.S.-supported interim government and its institutions, particularly the police and armed forces but also including universities.

Iraqi police reported yesterday that Sabri Bayati, a professor who headed the geography department at Baghdad University, was shot and killed by unknown gunmen as he left the campus.