Three nearly simultaneous bomb blasts tore through hotels in Amman, Jordan, killing at least 57 people from six countries, including the United States, and wounding 96 more than 50 people.

The insurgent organization al-Qaeda in Iraq claimed responsibility for the Wednesday attack, which was the deadliest terrorist operation ever carried out in Jordan.

"After studying and observing the targets, the places of execution were chosen to be some hotels which the tyrant of Jordan has turned into a back yard for the enemies of Islam, such as the Jews and Crusaders," the group said in a statement.

The incidents marked the first time that al-Qaeda in Iraq has conducted a successful attack in another country. Its leader, Abu Musab al-Zarqawi, was born in Jordan and has sponsored at least a half-dozen other attempted bombings and attacks in the kingdom in an effort to replace the monarchy with an Islamic state, according to Jordanian and U.S. officials.

Each of the blasts targeted a hotel owned by a Western chain -- Hyatt, Radisson and Days Inn, although most of the dead and wounded were Jordanians.

The Palestinian Authority's ambassador in Amman that four Palestinian officials were killed in the blasts, including the head of military intelligence for the West Bank, Lt. Gen. Bashir Nafe, also known as Abu Walid.

About 300 Amman residents gathered in Abdul Nasser Square on Thursday to denounce the attacks and declare their support for the country's King Abdullah. They walked, chanting "death to al-Zarqawi," to the Radisson Hotel. After Friday prayers, about 2,000 marched and waved Jordanian flags.

-- Jonathan Finer, Craig Timberg and Naseer Mehdawi

A relative mourns a bombing victim at a cemetery southeast of Amman, Jordan. The group al Qaeda in Iraq claimed responsibility for the Wednesday explosions.