AMMAN, Jordan (CNN) -- Three nearly simultaneous explosions occurred Wednesday night at hotels frequented by westerners in downtown Amman, Jordan, killing at least 67 people and wounding more than 150 others, the deputy prime minister of Jordan said.

<##IMAGE##> There have been no claims of responsibility, Karim Kawar, the Jordanian ambassador to the United States, told CNN.

The blasts occurred at the Radisson, the Days Inn Hotel and the Grand Hyatt Hotel between 9 p.m. and 10 p.m. (2 p.m. and 3 p.m. ET). The three hotels are within a few hundred yards of each other.

Deputy Prime Minister Marwan Muasher said the largest blast occurred at the Radisson during a wedding celebration, set off by a suicide bomber wearing a belt packed with explosives. Most of the casualties there were Jordanian, he said. (Watch eyewitness describes the scene -- 2:46)

"We thought it was fireworks for the wedding, but I saw people falling to the ground," said Ahmed, a wedding guest who did not give his surname, according to The Associated Press. "I saw blood. There were people killed. It was ugly."

The blast at the Grand Hyatt also appeared to have been caused by a bomber wearing an explosive belt, Muasher said.

An American businessman there told the AP that a bomb exploded in the lobby.

"Several of my friends have died. The people who carried this out were cowards," he told AP without providing his name.

At the Days Inn, a car failed in an attempt to breach a security barrier and exploded outside the hotel, Muasher said.

"This is the first really extensive attack we"ve had, probably ever, in the kingdom," he said.

"This has come as a shock to all of us," Kawar told CNN. He added, "We try to be as vigilant as possible but, at the end of the day, we"re all vulnerable to such attacks."

Video from the scene showed hundreds of police and emergency officials cordoning off the area around the hotels. Inside the Radisson, a hole was blown into the ceiling of a ballroom and tables and chairs were strewn across the room.

Dozens of ambulances were lined up outside the hotels, loading up and speeding off, their sirens wailing.

At Khalidi Hospital, near the affected zone, Dr. Khalid Salayman said five people had died there and 12 were wounded, 10 of them lightly.

Among the casualties were Iraqis and Germans, he said.

American Dana Burde said she was in the lobby of the Radisson when the blast there occurred -- apparently inside a nearby banquet hall, where a wedding party was celebrating.

"We were sort of blown out of the room, but our group is all fine," she said.

"There was a lot of debris and, certainly, there were people killed," said Burde, a New Yorker who is in Amman attending a conference on refugee education.

She said she heard an explosion at the nearby Hyatt five minutes after the blast at the Radisson.

King condemns attacks
An Italian businessman who was in the Hyatt said he saw three apparently lifeless bodies there.

Jordanian Embassy officials in Washington said the blasts came without warning and that no Jordanian government officials were in any of the buildings.

Prime Minister Adnan Badran told Jordanian television that all government offices and schools would be closed Thursday.

Soon after the attacks, Jordanian King Abdullah condemned them, telling reporters, "Justice will pursue the criminals."

The king also vowed that Jordan "will be resilient," Kawar said. An emergency Cabinet meeting was called.

Prior to the millennium celebrations, the Radisson was the target of a plot that was broken up by Jordanian law enforcement.

Jordan helps train Iraqi troops and is host to the headquarters of many international aid agencies that pulled relief workers out of Iraq as the insurgency there deepened.

It also is the homeland of Abu Musab al-Zarqawi, the head of al Qaeda in Iraq and that country"s most-wanted terrorist.

"Obviously, he"s a prime suspect," Muasher told CNN.

In a written statement, Jordanian House Speaker Abdel Hadi Majali called the blasts "a criminal terrorist act."

Asked whether al Qaeda may have been behind them, he said: "There is definitely an organization behind these attacks. Al Qaeda tried before and we foiled some attacks, and this could be one of those times when they were able to bypass our security forces."

In August an al Qaeda-linked group claimed responsibility for rocket attacks that targeted but missed two U.S. warships in the Jordanian Red Sea port of Aqaba.

In that attack, two rockets struck a warehouse and a hospital in Aqaba, killing a Jordanian soldier, while a third struck the nearby Israeli port city of Eilat.

Jordanian authorities said the attackers were in contact with insurgent leaders in Iraq, who were kept informed of their progress.

U.S. offers help
Though the hotels cater to international travelers, it was not clear whether those people were targeted.

The Hyatt is the most expensive, followed by the Radisson and then the Days Inn. All three are commonly used by Jordanians, said a Westerner who has lived in Jordan for more than a year.

In Washington, a White House spokesman said the administration knew of no U.S. casualties.

The State Department had not recently issued travel warnings for Americans visiting Jordan.

U.S. Secretary of State Condoleezza Rice called the attacks "wanton acts of murder against innocent people."

She said the United States "has offered Jordan whatever assistance and support it may need in response to this horrific attack."

"Jordan has, of course, been a tremendous fighter and ally in the war on terror," she said.

A White House spokesman said President Bush "condemns in the strongest possible terms the vicious terrorist attacks against innocent civilians."

The United States has proposed sending a team of FBI agents to help determine details of the attacks, such as what type of explosives were used.

Asked who is suspected of masterminding the attacks, one State Department official cited al-Zarqawi.

Two U.S. intelligence officials concurred that the attacks bear the hallmarks of al-Zarqawi, who has expressed an interest in launching attacks outside Iraq.

Days Inn issued a statement saying four of its guests were wounded, three of them seriously, but no one had been killed.

In a written statement, the Hyatt said its management team is "working to assure the safety and relocation of guests," given that authorities had evacuated the hotel.

And a Radisson SAS statement said the company "is working closely with local authorities and emergency workers to provide aid to those who were injured."

CNN"s Hala Gorani contributed to this report.