American troops fired on vehicles trying to drive through roadblocks, killing at least five people, including one child, in two separate incidents, the U.S. military said Tuesday.

One shooting in Baghdad took place in a northern neighborhood known to be a Shiite militia stronghold as the driver of a minibus collected employees to go to work at the Rasheed bank, police said.

U.S. troops fired on the bus after the driver approached a U.S. roadblock Tuesday morning and tried to drive through. As many as four passengers were killed, including three women, police and hospital officials said.

In a statement, the American military said the driver was traveling on a street restricted to cars, and failed to heed a warning shot. The U.S. statement said only two people were killed and four wounded. A manager at Rasheed bank also said the shooting claimed two lives.

The dead and injured were taken to Kindi Hospital, hospital officials said. The police and hospital officials spoke on condition of anonymity because they were not permitted to release information about the shooting.

During a U.S. operation Monday against al-Qaida in Beiji, 155 miles north of Baghdad, American troops shot at a vehicle speeding toward a roadblock after firing warning shots, the U.S. military said in a separate statement. Two men in the vehicle were killed immediately, and a child traveling with them died later of his wounds.

"We regret that civilians are hurt or killed while Coalition forces work diligently to rid this country of the terrorist networks that threaten the security of Iraq and our forces," Cmdr. Ed Buclatin, a U.S. spokesman, said in the statement.

The Shaab neighborhood in northern Baghdad where Tuesday's shooting took place is the same district where masked gunmen on Sunday killed 11 relatives of a journalist critical of the Iraqi government, according to colleagues and the media advocacy group Reporters Without Borders.

Interior Ministry spokesman Abdul-Karim Khalaf, however, denied the Sunday killings had taken place. "The killing of the 11 family members did not take place and that is totally confirmed," he told The Associated Press Tuesday.

In Amman, in neighboring Jordan, the journalist challenged the Iraqi government's account and accused the Interior Ministry forces of involvement in the deaths. Dhia al-Kawaz said they raided a wake in Iraq for his slain family Tuesday in the predominantly Shiite city of Kut, 100 miles southeast of Baghdad, tearing down banners commemorating the dead.

Al-Kawaz, who has lived outside Iraq for 20 years, said the killing of his family members was "a message to me and to any journalist inside Iraq or outside Iraq who opposes the policies of the Iraqi government."

Around Baqouba, the capital of violent Diyala province about 35 miles northeast of Baghdad, a suicide bomber targeting the local police headquarters killed six people, including three women, according to police.

East of the city, mortar rounds apparently targeting a local radio station instead landed near homes in the vicinity, killing two people, while a roadside bombing killed one civilian, police said.

Tuesday's violence underlined the fragility of security gains made recently by U.S. and Iraqi troops in Baghdad and other areas, and came one day after President Bush and Iraqi Prime Minister Nouri al-Maliki signed an agreement setting the foundation for a potential long-term U.S. presence in Iraq.

Details of the military, economic and political relationship will be negotiated in 2008, with a completion goal of July, when the U.S. intends to finish withdrawing the five combat brigades sent in 2007 as part of a troop buildup that has helped curb sectarian violence.

The U.S.-Iraq agreement will replace the present U.N. mandate regulating the presence of the U.S.-led forces in Iraq. Al-Maliki said the agreement provides for U.S. support for the "democratic regime in Iraq against domestic and external dangers."

It also would help the Iraqi government thwart any attempt to suspend or repeal a constitution drafted with U.S. help and adopted in a nationwide vote in 2005. That appeared to be a reference to any attempt to remove the government by violence or in a coup.

In Baghdad, Iraqis on Tuesday had mixed reaction to the deal.

Hamza Mohammed, praised the agreement, saying it would "liberate Iraq."

But Karim Abdullah said it was an attempt by Bush to salvage the end of his term and called it "just propaganda."

"We, as Iraqis, hope that our country will be liberated from the U.S. troops completely," he said.