Nine men wearing Iraqi police uniforms burst into an elementary school in a village south of the capital on Monday, ordered the five male teachers and the school bus driver into a room and killed them in a spray of bullets.

No children were hurt in the attack, which Iraqi officials said was the first of its kind to directly target schoolteachers.

"These men were terrorists wearing police uniforms," said police Capt. Muthanna Ahmed in Babil province. "No prior warning was made."

Ahmed said the teachers and driver were Shiite Muslims from Hilla who commuted together by bus to the school in the village of Muelha near Iskandariyah, about 30 miles south of the capital. The area, known as the Triangle of Death, is one of the most dangerous in Iraq. Travelers who pass through on their way to southern Iraq are routinely stopped by insurgents manning illegal checkpoints. Shiites, government workers and people associated with the U.S. military often are killed on the spot.

In other attacks around the country, officials reported that at least 11 Iraqis and three U.S. soldiers were killed.

In Baghdad, a suicide bomber detonated a vehicle outside the Iraqi Oil Ministry compound. The attacker rammed into a bus carrying ministry employees, killing seven police officers and three government workers, said Col. Haitham Sami, an Interior Ministry official. The charred bus smoldered just outside the concrete barriers that surround the ministry.

Government compounds in Iraq are heavily guarded and shielded with such barriers. But guards, police officers and employees often are targeted as they pass through security checkpoints.

Three U.S. soldiers were killed in two roadside bomb attacks in western Baghdad and southeast of the capital. No further details were reported.

In Baqubah, unknown gunmen assassinated Raad Hussein Jabar, a member of the city council. He was shot in the Hashmiya neighborhood as he was leaving a market, said Majeed Sabe, a physician at Baqubah General Hospital.

Attacks on Iraq's Shiite- and Kurdish-dominated transitional government have increased before the Oct. 15 referendum on a constitution that would set the framework for a more federalist form of government. Some Sunni Muslims among the country's Arabs have vowed to defeat the constitution, fearing it gives too much power to the majority Shiites, who have formed a pact with ethnic Kurds in northern Iraq. Sunni Arabs make up about 20 percent of the population but enjoyed broad power under President Saddam Hussein, who was ousted in 2003 in the U.S.-led invasion.

Jordanian-born Abu Musab Zarqawi, who leads the group al Qaeda in Iraq, has declared an insurgent war on Shiites.

In recent weeks, Shiite businessmen in Baghdad have been gunned down and bombers have targeted their shops. Shiites were mostly merchants under Hussein because government posts went largely to Sunnis. In one Sunni-dominated neighborhood this week, two Shiites who owned ice cream parlors were shot and killed.

Shiites and Kurds elsewhere in Iraq also have been targeted for attack.

In the Shiite holy city of Najaf in southern Iraq, insurgents were able to penetrate the headquarters of the Kurdistan Democratic Party, planting a bomb that exploded on Monday. Raed Mousa, a party member in Najaf, said the blast collapsed part of the building and wounded three guards. "This attack tries to create strife between the Kurds and their brothers in Shiites. This will never happen," Mousa said.

Defense officials in Washington on Monday reported the killing over the weekend of a top deputy to Zarqawi, identified as Abu Azzam, the Associated Press reported.

In a rare meeting with Western-affiliated groups, radical Shiite cleric Moqtada Sadr, whose militiamen battled U.S. and Iraqi forces in Baghdad on Monday, met with a delegation of Americans and Canadians from the Islamic Team for Making Peace and the Canadian Peace Makers. Sami Rasouly, who identified himself as a delegation spokesman, said the group was "searching for the truth about what is happening in Iraq now, and we intend to convey that truth . . . to the world."

Rasouly called Sadr "a man of peace, but he was made the target of a fierce attack by the occupation forces last year and tried with his followers to defend the city, the properties and the sacred places."

A spokesman for Sadr in Najaf said the cleric told the visitors that "American and British forces came to Iraq on the pretext of international law and order and democracy, but they have violated both."

Also Monday, a top Shiite politician vowed not to engage Sunni opponents in warfare.

"We always warned of the violence against Shiites. No one believed us," said Ammar Hakim, a member of Iraq's National Assembly and deputy head of the Supreme Council for the Islamic Revolution in Iraq, a major Shiite political party. Hakim, speaking to Iraqi reporters at a news conference in Amman, Jordan, said the violence would not lead to civil war between Shiite and Sunni Muslims.

"The Sunnis are our brothers in religion and country," he said. "These are terrorist groups claiming to belong to certain ethnic groups. We, Shiites and Sunnis, should unite to defeat these terrorist groups."

Sarhan reported from Najaf. Special correspondents Bassam Sebti in Baghdad, Hassan Shammari in Baqubah and Omar Fekeiki in Amman contributed to this report.