There was no immediate claim of responsibility for the attack. An al Qaeda offshoot group called Jund al-Sham was suspected, said Syria's ambassador to the U.S., Imad Moustapha, in comments to an American television network. The radical fundamentalist group has been blamed for several attacks in Syria in recent years, he said.
"It does have the hallmark of an al Qaeda-type of attack, if we look at the fact that it seemed to be a vehicle, a bomb, with people inside, showing that it would be a suicide attack," Sajjan Gohel, terrorism analyst at the Asia-Pacific Foundation in London, told CBS Radio News.
The rigged canisters were almost identical to the makeshift bombs shown in a new video by a militant Islamic group circulating on the Internet, CBS News correspondent Richard Roth reports. But the life-saving difference in Damascus was that the canisters didn't detonate.
And protected by the Syrians' quick response, and the compound's high walls, the embassy wasn't hit and American diplomats weren't hurt.
Later Tuesday, Secretary of State Condoleezza Rice praised the work of Syrian security agents in repelling an attack against the U.S. Embassy in Damascus, but said it was too early to say who might have been behind it.
"I think it's very early to try and speculate why this may have happened," said Rice, speaking at a news conference in Nova Scotia Tuesday with her Canadian counterpart, Peter MacKay.
In the past, the Bush administration has been very critical of the tight control that the regime of Syrian President Bashar Assad has over its people. But Rice would not speculate on whether the attack may be an indication that the regime's control is slipping.
In Washington, White House Press Secretary Tony Snow thanked the Syrian officials who assisted Americans after Islamic militants tried to storm the embassy.
"Syrian officials came to aid of the Americans," Snow told reporters. "The U.S. government is grateful for the assistance the Syrians provided in going after the attackers, and once again, that illustrates the importance of Syria being an important ally in the war on terror."
American authorities have long accused Syria of backing the insurgency in Iraq, and for arming the terror group Hezbollah in Lebanon. But U.S. officials hope in the aftermath of the attack, the two countries can possibly begin to work together to fight terrorism again, CBS News' Charlie D'Agata reports.
"It does not mean they are an ally. We are hoping they will become an ally and make the choice of fighting against terrorists," he added.
Snow said the administration does not know who is responsible for the attack.
"They're taking a look," he said. "There have been no claims of responsibility and we have not had an opportunity to dig down and find out. We just don't know."
The attack might also be a non-al Qaeda group, Gohel said.
"We know that the Syrian regime has allowed insurgents to cross back and forth to attack coalition troops. It also has harbored a lot of Hezbollah members in the past. We can't rule out the possibility that Hezbollah has played a role in this," Gohel said.
Authorities so far are saying nothing about the one terrorist captured alive — except that they're questioning him, Roth reports.
One of Syria's anti-terrorism forces was killed and 11 other people were wounded, the official news agency reported. The wounded including a police officer, two Iraqis and seven people employed at nearby technical workshop.
A Chinese diplomat also was hit in the face by shrapnel and slightly injured while standing on top of a garage at the Chinese Embassy, China's Foreign Ministry said. The diplomat, political counselor Li Hongyu, was in stable condition at a hospital, the ministry said.
A witness said a Syrian guard outside the U.S. Embassy also was killed, but the government did not immediately confirm that. As at most American embassies worldwide, a local guard force patrols outside the compound's walls while U.S. Marines are mostly responsible for guarding classified documents and fighting off attackers inside the compound.
Witnesses also said the gunmen tried to throw hand grenades into the embassy compound, shouting "Allahu akbar!" or "God is great!" It was not clear if any of the grenades made it over the walls, which are about 8 feet high.