More violence struck Iraq ahead of the anniversary of the start of the U.S.-led war that ousted Saddam Hussein (search): a deadly car bomb exploded Thursday, three U.S. soldiers died in mortar attacks and five Iraqi journalists were shot to death.

The U.S. military, meanwhile, lowered the death toll in a suicide bombing at a Baghdad hotel on Wednesday to seven.

Officials had earlier said 27 people were killed in the Baghdad bombing. It then revised that downward to 17 dead without elaborating. Hours later, the military said that just seven had been killed.

There was no clear explanation for the change but Iraq doesn't have a centralized system for handling such tragedies, and with the bodies of victims going to different morgues, government departments and other agencies often disagree over death tolls.

The suicide car bombing occurred near a hotel in Basra (search) as a British military patrol passed by, killing two men and a boy in addition to the bomber. A man who got out of the car before the blast was stabbed to death by passers-by.

Three of the journalists were killed as they drove to work at a coalition-funded television station in Baqouba, 35 miles northeast of Baghdad. Nine other employees of Diyala TV (search) were wounded in the attack on their minibus, said Sanaa al-Daghistani, the station's information director. Rebels often target Iraqis perceived as collaborators with the occupation.

Two more journalist died in separate violence when American soldiers shot and killed a cameraman from an Arab station and critically wounded a correspondent in Baghdad, the station said. The correspondent died of his wounds in a hospital early Friday, said Mohammed Ibrahim, the station's editing supervisor in Baghdad.

The all-news station Al-Arabiya, based in the United Arab Emirates, said cameraman Ali Abdel-Aziz and correspondent Ali al-Khatib were hit as they covered a nighttime rocket attack on Burj al-Hayat hotel in the capital.

Cpl. Craig Stowell, a U.S. military spokesman, said "one Iraqi was shot and killed when he tried to run a checkpoint near Burj al-Hayat hotel at 22:16." Stowell had no further details.

The New York-based Committee to Protect Journalists (search) said it would investigate the circumstances surrounding the four deaths.

At the United Nations, Secretary-General Kofi Annan (search) said he is sending a U.N. team back to Iraq "as soon as possible" in response to an Iraqi request for help in organizing the political transition and elections.

Late Thursday, insurgents targeted the Ministry of Oil and the Bourj al-Hayat Hotel in Baghdad with several rockets and explosive devices. There were no injuries. One projectile punctured a hole in the second floor of the hotel, which sometimes houses Kurdish politicians.

Sirens also wailed briefly in the area housing the U.S.-led coalition headquarters. A U.S. military official said there had been an attack and it was under investigation. There were no casualties.

It was unclear whether insurgents were timing attacks to overshadow the anniversary of the March 20, 2003, start of the war that toppled Saddam, though assailants have often conducted attacks on holidays and other significant dates.

The aim of anti-U.S. forces appears to be to demonstrate that Iraq is ungovernable despite some American progress in its nation-building effort, including the formation of an Iraqi police force, the signing of an interim constitution and plans to hand over power to Iraqis on June 30.

"We were fighting them knowing full well the better we did the harder it would get," said Maj. Gen. Martin Dempsey, commander of the U.S. Army's 1st Armored Division, which oversees security in Baghdad. He said the fight in Iraq was evolving into a battle against shadowy extremists who attack civilians rather than soldiers.

"It is far easier to fight an enemy who fights you conventionally and who fights you in some similar fashion to the way you fight him, than it is to fight an enemy who uses the tools of terror," he said.

A man suspected of involvement in the Basra bombing who left the vehicle shortly before the blast was caught by passers-by and stabbed to death, said police Lt. Col. Ali Kazem. Two others spotted getting out of the vehicle were caught by members of the public and later arrested.

At least 15 people were wounded, three seriously, hospital officials said. No British soldiers were wounded.

Unlike other areas of Iraq, Basra has been relatively calm.

Insurgents also fired mortar rounds at two U.S. military bases on Wednesday, killing three American soldiers and wounding nine others, the U.S. military said Thursday. The deaths brought to 567 the number of U.S. troops killed in Iraq since the start of hostilities last year, according to Defense Department figures.

Brig. Gen. Mark Kimmitt said 35 people were wounded in Wednesday's car bombing, which destroyed the Mount Lebanon Hotel in Baghdad. Scott Mounce, 29, of Scotland was killed and another Briton was wounded, the British government said.

U.S. Army Col. Jill Morgenthaler said the attack was a suicide bombing but said the hotel may not have been the intended target because the explosives-laden vehicle was in the middle of the street and not in front of the hotel.

The hotel is in a busy district of commercial and residential buildings. The explosion set ablaze nearby homes, offices, cars and shops, sending dazed and wounded people stumbling from the wreckage.

Dempsey said if the hotel was the target, the attack bore a closer resemblance to targets of Ansar al-Islam, an extremist group with apparent links to Al Qaeda.

The network of Al Qaeda-linked Jordanian Islamic militant Abu Musab al-Zarqawi (search) usually attacks Iraqi targets — Shiite pilgrims or Iraqi police — with an aim to sowing discord and perhaps civil war.

An unidentified Jordanian suspected of having links with al-Zarqawi was arrested recently on the outskirts of Baghdad, Dempsey said. The detainee was caught with a bomb.

The Mount Lebanon was a so-called "soft target" because it did not have concrete blast barriers and other security measures that protect coalition offices and buildings where Westerners live and work.

In the restive town of Fallujah on Thursday, insurgents with AK-47 rifles and rocket-propelled grenades clashed with U.S. troops guarding a government building. One civilian died and another was wounded, witnesses said. The U.S. military said eight U.S. soldiers and a Marine were wounded when a mortar round hit a roof.