Moments before the convoy carrying Abizaid and Maj. Gen. Charles Swannack, commander of the 82nd Airborne Division, entered the cinderblock walls at the headquarters of the Iraqi Civil Defense Corps, attackers fired grenades and assault rifles from nearby rooftops.
U.S. troops returned fire and the convoy pulled away. Abizaid and Swannack cancelled plans to walk into the city and returned to a nearby U.S. military base.
A Pentagon official in Washington, speaking on condition of anonymity, said it was likely the insurgents were tipped off to the presence of a senior general, but U.S. military spokesman Brig. Gen. Mark Kimmitt said he was not prepared to make that link.
Attacks against U.S. forces and their Iraqi allies have increased in recent days. Two suicide bombings this week killed as many as 100 people as they waited outside a police station and army recruiting station in Baghdad to apply for jobs.
Two American soldiers were killed and another wounded Wednesday evening by a roadside bomb in Baghdad, the U.S. military said.
Amid the violence, a team from the United Nations met with influential Shiite cleric Grand Ayatollah Ali al-Sistani, who has demanded direct national elections before the scheduled June 30 transfer of power.
After the two-hour meeting at al-Sistani's home in Najaf, the head U.N. envoy, Lakhdar Brahimi, told reporters that the cleric was still insisting on the early elections. But Brahimi did not say there was agreement on a timeframe for the vote.
"We are with him 100 percent because elections is the best way to establish a state that serves the interests of its people," Brahimi said, adding that al-Sistani and the U.N. experts did agree that elections should be "well-prepared."
The U.S. plan calls for a temporary legislature to be picked by regional "caucuses" so the June 30 transfer can occur. Under the proposal, national elections would not happen until early 2005.
Al-Sistani's demands for elections held before June 30 led to demonstrations by tens of thousands of his supporters and helped prompt the Bush administration's request to the United Nations to deploy a team to assess the feasibility of such a vote.
U.S. officials say they're willing to adjust the caucuses plan but resist any delay in the June transfer, according to the Associated Press.
The Arab newspaper Al-Hayat quoted sources close to al-Sistani saying if experts feel elections can be organized within 10 months, he is willing to delay the handover of sovereignty, or carry out a partial handover, long enough to allow the vote to take place, the AP reported.
Al-Sistani also wants an elected legislature to approve a temporary constitution still being drafted, rather than the U.S.-selected Iraqi Governing Council.
Shiites, thought to compose 60 percent of Iraq's 25 million people, have long been ruled over by Sunnis and would likely dominate any nationwide vote. This has raised concerns both for American administrators, but also for minority Sunnis and ethnic Kurds. American officials have proposed regional caucuses as a way to ensure more representation of the different groups.