(AP) At least one American was among the 56 people killed by suicide bombers in attacks on three U.S.-based hotels Wednesday night, a U.S. Embassy official said Thursday. At least two other Americans were wounded. The victims were not identified. The official spoke on condition of anonymity in accordance with embassy rules.

Also Thursday, hundreds of angry Jordanians rallied outside one of the hotels, shouting, "Burn in hell, Abu Musab al-Zarqawi!" after the terrorist's group claimed responsibility for the blasts.

In an Internet statement, al-Qaida in Iraq linked the blasts at the Grand Hyatt, the Radisson SAS and the Days Inn hotels to the war in Iraq and called Amman the "backyard garden" for U.S. operations.

Police continued a broad security lockdown and authorities sent DNA samples to identify the attackers. Land borders closed for nearly 12 hours were reopened.

The Amman protest was organized by Jordan's 14 professional and trade unions _ made up of both hard-line Islamic groups and leftist political organizations _ traditional critics of the king's moderate, pro-Western policies.

Protesters shouted, "Death to al-Zarqawi, the villain and the traitor!" Honking vehicles were decorated with Jordanian flags and posters of the king. A helicopter hovered overhead.

"We sacrifice our lives for you, Amman!" the protesters chanted.

Other rallies were held across the kingdom, including the Red Sea port of Aqaba, where attackers using Katyusha rockets narrowly missed a U.S. ship and killed a Jordanian soldier in August. Others were in al-Zarqawi's hometown of Zarqa and the southern city of Maan, which is a known hub for Muslim fundamentalists.

Amman's streets were deserted early Thursday, which was declared a day of mourning. Public and private offices were closed under government instructions, apparently to allow tightened security measures to take hold.

The date of Wednesday's attack, Nov. 9, would be written as 9/11 in the Middle East, which puts the day before the month. A Jordanian government spokesman declined to speculate on its meaning. But Jordanians were sending text messages that read: "Have you noticed that today is 9-11, similar to America's 11-9?"

In Washington, the White House said the bombings have "the hallmarks of al-Qaida," but spokesman Scott McClellan said there has been no definitive conclusion yet about who was responsible.

President Bush called King Abdullah II on Thursday to express condolences.

Both agreed to reiterate to the world that "the terrorists cannot shake our will and our determination to defeat their hateful, murderous ideology," McClellan said.

Government spokesman Bassel Tarawneh said 56 people were killed in the suicide attacks, but he said that number likely would rise. In addition to the American, the victims included 33 Jordanians, six Iraqis, two Bahrainis, two Chinese, one Saudi and one Indonesian. He could not identify the rest.

The Palestinian envoy to Amman said the victims included two high-ranking Palestinian security officials, a senior Palestinian banker and the commercial attache at the Palestinian Embassy in Cairo, Egypt.

Maj.-Gen. Bashir Nafeh, the head of military intelligence in the West Bank, and Col. Abed Allun, a high-ranking Preventive Security forces official, were killed in the attack at the Grand Hyatt Hotel, Ambassador Attala Kheri told The Associated Press.

An east Jerusalem businessman, Bashar Qadoumi, also was killed, his family said.

Tarawneh said 96 people were wounded, although police said more than 115 were hurt. Police detained several people, although it was unclear if they were suspects or witnesses.

"They are being interrogated as we speak," police spokesman Maj. Bashir al-Da'aja told the AP.

The official Petra news agency quoted doctors who treated the injured as saying many wounds were inflicted by ball bearings used in the bombs.

The al-Qaida claim said Jordan was a target because it was "a backyard garden for the enemies of the religion, Jews and crusaders ... a filthy place for the traitors ... and a center for prostitution." Its authenticity could not be independently verified, but it appeared on an Islamic Web site that is a clearinghouse for statements by militant groups.

The claim said the attacks put the United States on notice that the "backyard camp for the crusader army is now in the range of fire of the holy warriors."

The hotels, frequented by Israelis and Americans among other foreign guests, have long been on al-Qaida's hit list.

Iraqi government spokesman Laith Kubba said the attack should alert Jordan that it needed to stop hosting former members of Saddam Hussein's regime.

"I hope that these attacks will wake up the `Jordanian street' to end their sympathy with Saddam's remnants ... who exploit the freedom in this country to have a safe shelter to plot their criminal acts against Iraqis."

He also said Iraqis may have had a hand in the attacks.

Palestinian legislator Hanan Ashrawi said she did not believe al-Qaida "or any of these violent extremists have had support among mainstream Arab opinion at all. Now they are making sure they are turning everyone against them."

Initial police reports showed that the suicide bomber at the Grand Hyatt was possibly Iraqi, a Jordanian security official said on condition of anonymity. He said the middle-aged man, who had explosives under his suit, was stopped by suspicious security officials in the lobby.

Speaking in an Iraqi accent, the man said he was "looking around," and then blew himself up, the official added, saying hotel cameras had some shots of him.

Deputy Prime Minister Marwan Muasher said al-Zarqawi, who has a $25 million U.S. bounty on his head, was a "prime suspect." The Jordanian-born al-Zarqawi is known for his animosity to the country's Hashemite monarchy. The claim of responsibility did not name Abdullah but twice referred to the "tyrant of Jordan."

The suicide bombers struck just before 9 p.m. One explosion occurred in a hall at the Radisson where 300 guests were celebrating the wedding of Ashraf Akhras and Nadia Alami, both Palestinians. They survived, but both their fathers were killed, along with 11 other relatives.

Ibrahim Akhras, the groom's cousin, said he had left the hotel to buy flowers and was just returning when the blast went off.

"I found huge devastation in the hall. I saw bodies and blood. The ceiling of the hall collapsed over the people, and I saw kids and women screaming in their blood," he said.

"No religion, no Islam, no Muslim people allow this to happen."

In the West Bank village of Silet al-Thaher, the Akhras clan set up a house of mourning, and 35-year-old Najah Akhras, who lost two young nieces, cried and shouted: "Oh my God, oh my God! Is it possible that Arabs are killing Arabs, Muslims killing Muslims? For what did they do that?"

Al-Da'aja said the attacker at the Days Inn tried to detonate himself inside the hotel lobby, but his bomb did not go off until he rushed outside the hotel lobby. Initial reports said the hotel was attacked by a car bomb.

Until late Wednesday, Amman _ a comfortable, hilly city of white stone villas and glitzy high-rises _ had mostly avoided large-scale attacks and was a welcome sanctuary of stability in a troubled region.

Al-Zarqawi is most known for devastating suicide attacks in Iraq, often against U.S. targets but also against Shiite Iraqis. He has shown a flair for propaganda and drawn wide support among militants in the region.

But outside Iraq, and especially in Jordan, he has been equally active.

He was sentenced to death in absentia by a Jordanian military court for the 2002 assassination of a U.S. diplomat, Laurence Foley, in Amman.

His group also is accused of previously trying to blow up the Radisson in Amman as part of the so-called Millennium plot in 1999 and of the August attack at the Jordanian port of Aqaba. In Amman, a security official said authorities had tips on suspects who are being hunted, including possible sleeper cells or individuals who may have assisted the attackers and later fled in a vehicle bearing Iraqi license plates.