Three Islamic militants suspected to have Al Qaeda ties were killed Tuesday after a failed attempt to attack the U.S. Embassy with automatic rifles, hand grenades and a van rigged with explosives. A Syrian security officer was also killed, but no Americans were hurt.

Secretary of State Condoleezza Rice said it was too early to know who was behind the attack, while Syria's ambassador to the U.S., Imad Moustapha, told a major news network that an Al Qaeda offshoot group called Jund al-Sham was responsible. The radical fundamentalist group has been blamed for several attacks in Syria in recent years, he said.

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.

The attackers apparently did not breach the high walls surrounding the embassy's white compound in the city's diplomatic neighborhood.

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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.

The attack came at a time of high tension between the United States and Syria over the recent Israeli-Hezbollah war in neighboring Lebanon. In Damascus, the sentiment has become increasingly anti-American.

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Syria has seen previous attacks by Islamic militants. In June, Syrian anti-terrorism police fought Islamic militants near the Defense Ministry in a gunbattle that killed five people and wounded four. In 2004, four people were killed in a clash between police and a team of suspected bombers targeting the Canadian Embassy.

The Bush administration has been critical of the tight control that the regime of Syrian President Bashar Assad has over its people. Rice, meeting with her Canadian counterpart in Nova Scotia, would not speculate on whether Tuesday's attack may be an indication that the regime's control is slipping.

White House press secretary Tony Snow also expressed gratitude to Syria.

"Syrian officials came to aid of the Americans," Snow said. "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.

"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 said, adding that the Bush administration does not know who is responsible for the attack.

Washington recalled Ambassador Margaret Scobey after the assassination of former Lebanese Prime Minister Rafik Hariri in 2005, amid suspicions that Damascus had a role in it. She has not returned since, effectively downgrading U.S. diplomatic representation to the level of charge d'affaires.

Pools of blood lay on the sidewalk outside the U.S. Embassy, near a burned car apparently used by the attackers. A sport utility vehicle with U.S. diplomatic tags had a bullet hole in its windshield, and the windows of nearby guard houses also were shattered.

There were conflicting reports of what happened.

Syrian TV said one car was rigged with explosives but never was detonated by the attackers. But one witness said a second car did explode, and TV video showed a burned car.

The Interior Ministry, which is in charge of police, said a fourth attacker now in detention was wounded in what it called a "terrorist attack." The report, carried on state-run television, said anti-terror units brought "the situation under control" and an investigation was under way.

In Washington, a State Department spokesman confirmed the attack by "unknown assailants" but had few details. "Local authorities have responded and are on the scene," said spokesman Kurtis Cooper said.

A U.S. Embassy statement said the embassy came under armed attack at 10:10 a.m. and that all embassy personnel were safe. One Syrian guard was injured by gunfire and was hospitalized in a stable condition, the statement said.

The embassy's charge d'affaires, Michael Corbin, met with Interior Minister Bassam Abdel Maguid at the scene, and spoke by phone with assistant minister of foreign affairs, Ahmed Arnous, according to the statement.

It said the Syrian government has pledged full security cooperation.

About 30 Syrian guards usually are posted around the embassy 24 hours a day, Moustapha said.

State television said four armed attackers "attempted to storm" the embassy, using automatic rifles and hand grenades. Syrian security guards attacked the gunmen, killing three and wounding a fourth, TV said.

The attackers came in two cars and parked one that was rigged with explosives in front of the embassy but did not blow it up, state-run TV reported. Explosives experts dismantled the bomb, it said.

But a witness told The Associated Press that two gunmen drove up in front of the embassy, got out of their car, shot at the Syrian sentries at the building's entrance, and then detonated explosives in the car.

The witness, who spoke on condition of anonymity because of the sensitivity of the matter, said the security personnel fired back, and security forces rushed to the scene.

Television showed a delivery van loaded with pipe bombs strapped to large propane gas canisters outside the embassy. Had the bombs detonated, the explosions could have caused massive damage.

The video also showed the charred remains of a smaller car parked several feet behind the van.

Up to 40 U.S. diplomats are posted at the embassy, which is "average" in size, according to Tom Case, a deputy spokesman at the State Department.

The Associated Press contributed to this report.

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