A U.S. soldier was wounded when a rocket-propelled grenade damaged a Humvee car in central Baghdad on Thursday, in the latest of a spate of increasingly bold guerrilla-style attacks, Iraqi witnesses said. At least two Iraqi passers-by were also wounded in the attack which took place shortly after 10 a.m. The soldier was given first aid by his comrades on the scene while the Iraqi casualties were taken to hospital. Iraqis then set the damaged Humvee on fire, hurling stones and shoes at the burning vehicle. At least one Iraqi civilian car was hit in the attack and at least one of its occupants was wounded. Heavily armed U.S. soldiers deployed in the area. U.S. forces have come under attack almost daily in recent weeks. At least 23 American soldiers have been killed in Iraq since major combat was declared over in May after U.S.-led forces overthrew Saddam Hussein. Six British soldiers died in the same period. The attacks have continued despite a crackdown by occupation troops in areas to the northeast and north of the capital. Also Wednesday, a U.S. Marine was killed and three others were injured while clearing mines near the south-central Iraqi city of Karbala, the U.S. military said. The cause of their deaths was not immediately released. **U.S., U.K. Vow to Stay on Track in Iraq*** Meanwhile the British foreign minister and American senators visiting Iraq on Wednesday played down concerns that the U.S.-led occupation risks descending into a Vietnam-style quagmire, saying the remnants of Saddam Hussein's regime will be crushed. "A quagmire? No," Jack Straw told reporters at the British mission in Baghdad. "These actions against the coalition forces won't succeed and will be dealt with." The comments coincided with a statement by President Bush on Wednesday vowing that anti-U.S. attacks would not keep the United States from fulfilling its mission in Iraq. "We are taking the fight to the enemy," said Sen. Pat Roberts, a Republican of Kansas, one of nine U.S. senators on a three-day tour of Iraq. He and the other senators traveled Wednesday to the northern city of Kirkuk, where they grilled U.S. military officers about the recent spate of anti-American attacks and the hunt for Saddam's alleged weapons of mass destruction. To quell the burgeoning resistance, U.S.-led forces have launched a series of lightning raids across Iraq. One such operation northeast of Baghdad, dubbed Operation Sidewinder, entered its fourth day Wednesday. U.S. officials insist there is no nationally coordinated resistance to the occupation, and it remains unclear exactly which groups are staging attacks - though most suspicion falls on Saddam's former security forces. On Wednesday, a videotape aired on Lebanon's Al Hayat-LBC satellite station showed a man claiming to belong to the previously unknown "Independent National Commando Front" and threatening new attacks. The man - who appeared with his head covered by a checkered Arab headdress alongside three other men, all carrying rifles - claimed that in one recent anti-U.S. attack "there was cooperation between us and another organization." He said the larger the U.S. military presence in Iraq, "the stronger our hits and effects will be." Several other shadowy groups have made similar claims in recent weeks. The man said some of the resistance is from Saddam loyalists but said his group was "independent." Bush pledged Wednesday that the United States will deal harshly with those who attack American troops, and said such violence will not undercut his resolve to keep Americans there until stability is restored. "Anybody who wants to harm American troops will be found and brought to justice," Bush said at an impromptu news conference at the White House. "There are some who feel like if they attack us, we may decide to leave prematurely. They don't understand what they're talking about if that's the case." On Wednesday, a leader of a prominent Shiite group accused the Bush administration of reneging on pledges to hand over power to local political groups in Iraq. Hamid al-Bayati, of the Shiite Supreme Council for the Islamic Revolution in Iraq, also blamed Americans for failing to secure Iraq after Saddam's fall and "plunging the country into an unending cycle of violence." "They kept promising us Iraq would be ruled by its people once there was a regime change and Saddam was removed, but that didn't happen and seems far from happening," he told The Associated Press from his London office. On Saturday, Ayatollah Ali Husseini al-Sistani issued a fatwa, or religious edict, denouncing U.S. plans for a council to draw up a new constitution and demanding elections so that Iraqis can choose their own constitutional convention. **PHOTO CAPTION*** U.S. Army soldiers patrol the restive town of Fallujah June 2, 2003. (Faleh Kheiber/Reuters)