Syria sealed off the US embassy in Damascus after an apparent failed bomb attack.
Emergency services were at the scene after a clash in which three alleged attackers were killed.
Windows in the embassy were hit by bullets.
TV footage from Damascus showed a burnt-out car outside the compound.
A van, which appeared undamaged, was also shown.
Inside were what appeared to be gas canisters.
Some of the van's contents were unloaded on to the street.
Children were attending school nearby during the clash.
Syrian security forces patrolled the area in force.
No US citizens appear to have been injured at the embassy which has its own American guards.