DAMASCUS, Syria (CNN) -- Syrian security forces killed four attackers Tuesday outside the U.S. Embassy in Damascus after a car exploded near the walls of the American compound, the Syrian Information Ministry said.

There was no claim of responsibility for the attack, but an al Qaeda offshoot group called Jund al-Sham -- or Soldiers of Levant is suspected, said Imad Moustapha, Syrian ambassador to the United States.

The radical fundamentalist group has been blamed for several attacks in Syria in recent years, Moustapha said.

One Syrian security guard protecting the embassy was killed in the attack, Syria's state-run news agency SANA reported. (Watch officials go through evidence from attack -- 5:43)

Syrian authorities wounded and arrested another suspected attacker, the ministry said.

No American diplomats were harmed.

SANA reported 13 others were wounded, including an embassy policeman, a security worker and 11 civilians, among them two Iraqis and a Chinese.

"The State Department confirms an attack by unknown assailants," U.S. State Department spokesman Kurtis Cooper said from Washington. "The event appears to be over and handled by local authorities ... on the scene."

The Syrian Information Ministry said none of the staff was wounded and the embassy incurred no damage.

Video footage from the scene showed the burned-out wreckage of a car and blood-soaked streets near the embassy, which in a residential area of the Syrian capital.

The armed attackers apparently tried to storm the embassy with hand grenades and machine guns after detonating a car bomb near the compound walls, according to the ministry and the state-run news agency.

Authorities confiscated a second vehicle filled with homemade bombs, according to SANA and video from the scene.

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

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

Casey cited "ongoing concern" about a possible attack in Syria and among U.S. embassies in the Middle East because of deteriorating relations.

The United States pulled its ambassador to Syria following the February 2005 assassination of former Lebanese Prime Minister Rafik Hariri, an attack partly blamed on the Damascus government.

CNN's Andrea Koppel and Elise Labott contributed to this report.

A security official stands Tuesday near a car damaged in the foiled attack on the U.S. Embassy in Damascus.