AMMAN, Jordan (CNN) -- Calling the al Qaeda in Iraq leader a "lowlife," Jordanians on Thursday flooded the nation's capital in bitter protest of the triple suicide bombings that shook the city a day earlier and killed at least 56 people, most of Arab descent."Burn in hell, Abu Musab al-Zarqawi!" hundreds of protesters shouted, denouncing the terrorist network's leader -- a Jordan native -- after an Internet posting stated his group was responsible for the attacks.Suicide bombings may be common in some parts of the Middle East but not in Jordan, and Wednesday's attacks on three Western-based hotel chains will only strengthen the resolve of Jordanians to keep terrorism from breaching its borders, said the country's King Abdullah II. "We will pursue those criminals and those who stand behind them, and we will reach them wherever they are," the stern-looking king said in his address on state television. (Watch a profile of terrorist Abu Musab al-Zarqawi -- 4:02)Abdullah, who has close ties to Israel and Washington and is considered a key U.S. ally in the war on terror, emphasized that violence and blackmail will never sway this nation of roughly 6 million people. "They will never make us retreat from combating terrorism in all its forms."It is Jordan's close ties to the West that made it a target for the attacks that wounded more than 100 at the Radisson, Grand Hyatt and Days Inn hotels, according to the Web posting attributed to al Qaeda in Iraq.The Web posting boasts that al Qaeda in Iraq operatives studied and targeted "retreats that were planted in the land of Muslims in Amman" and blamed Abdullah for allowing the hotels to be "a backyard for the enemies of faith -- the Jews and the crusaders."But Jordanians sided with their king Thursday, taking to the streets with the kingdom's red, white, black and green banner in hand. Some carried large photos of Abdullah and signs condemning the attacks.The protesters, which included parents with children, snarled traffic, and many commuters stopped to join the demonstrators or blared their car horns as they passed the scene. Jordanian schools and government offices were closed Thursday. Mea culpaA senior Jordanian intelligence official said suicide attackers with explosive belts caused the carnage and destruction, and the Web posting attributed to al Qaeda in Iraq states that the hotels were studied before they became targets.The posting also ties the attacks to the group's Islamist beliefs, a notion rejected by many Jordanians. "The world has to know that this has nothing to do with Islam," said Ashraf al-Akhras, who lost several family members when one of the bombs went off during his wedding.A later Web posting attributed to al Qaeda in Iraq seemed to respond to the outrage sparked by Wednesday's bombings, The Associated Press reported. Purporting too explain why "holy warriors targeted these dens," the posting states that the hotels were favorite haunts of Americans and Israelis. "Let all know that we have struck only after becoming confident that they are centers for launching war on Islam and support the crusaders' presence in Iraq and the Arab peninsula and the presence of the Jews on the land of Palestine," the posting states, promising "catastrophic" assaults in the future that would dwarf the hotel bombings, the AP reported.CNN could not verify if the Web postings were authentic, but U.S. intelligence officials called the claim "credible." Pentagon officials added that before the explosions a former hostage revealed that his captors had discussed such attacks on Western targets.Pentagon spokesman Lawrence DiRita said the attacks were consistent with other attacks carried out by al Qaeda. "It is certainly plausible that the claim of al Qaeda in Iraq is valid, but it's just not something that we're able to establish yet," he told reporters.CNN also has learned from a source familiar with the investigation that two of the bombers have been identified as Iraqis, and Jordanian police are narrowing their search for conspirators based on that information. Al Qaeda in Iraq leader, al-Zarqawi, has had a price on his head since last year. The $25 million bounty is the same amount the Pentagon is offering for al Qaeda leader Osama bin Laden. DiRita described al-Zarqawi, who is thought to be somewhere in Iraq, as a man "spending a lot of time trying to stay alive." However, the Pentagon spokesman was quick not to discount his reach. "That being said, he's still capable of conducting a tremendous amount of damage."(The making of a terrorist -- 4:02)Jordanian officials had said they would handle the investigation on their own, but they have since changed their minds. A small contingent of FBI personnel from the agency's laboratory division is traveling to Amman at the request of the Jordanian government, FBI spokesman Richard Kolko said Thursday. Another official said fewer than 10 agents would make the trip. Bush respondsShortly before the U.S. State Department confirmed that two Americans were killed and four were wounded in the attacks, President Bush told reporters he had called Abdullah and "expressed our nation's deep concern and compassion for those who lost their lives."Later, the president and first lady visited the Jordanian Embassy in Washington to express their sympathies.In a condolence book at the embassy, Bush wrote, "May God bless the people of Jordan during this difficult time. Please know the American people join you in prayer and spirit," Added Laura Bush, "And with love and sympathy to the people of Jordan." Referring to the perpetrators as a heartless enemy bent on "defiling a great religion of Islam," Bush stood with Jordanian Ambassador Karim Kawar and proclaimed, "This enemy must be defeated."The wedding tollPerhaps hardest hit by the blasts were groom al-Akhras and his bride, Nadia Alami, whose wedding reception at the Radisson was interrupted by the most devastating of the three blasts. (Watch what the explosion left behind -- 4:39)Though no Westerners were in attendance, one of the bombers targeted the wedding party as al-Akhras and Alami entered the wedding hall. The explosion killed both newlyweds' fathers, and al-Akhras lost as many as 10 relatives. "This is not Islam," al-Akhras said. "This is a terrorist fighting our capital."In the Palestinian West Bank village of Silet al-Thaher, Akhras family members mourned their relatives, the AP reported. "Oh my God! Oh my God! Is it possible that Arabs are killing Arabs, Muslims killing Muslims? For what did they do that?" screamed 35-year-old Najah Akhras, who lost two nieces in the attack. Palestinian officials among deadDespite being the supposed targets of the attacks, Westerners escaped their brunt, as most of the casualties were Jordanian. Jordanian Embassy officials said none of its government officials were wounded or killed.Other government officials were less fortunate, including Maj. Gen. Bashir Nafeh, head of Palestinian military intelligence, and Jihad Fattouh, the brother of the Palestinian parliament speaker, said chief Palestinian negotiator Saeb Erekat. The two were on their way back from Cairo, Egypt, he said.Also, three Chinese were killed and one wounded in the attacks, according to the Chinese news agency Xinhua, which cited a Chinese Foreign Ministry news release. The victims were members of a delegation from China's University of National Defense and were staying at one of the hotels, according to the report. The report did not specify which hotel. Copyright 2005 CNN. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed. Associated Press contributed to this report.