A man armed with an automatic weapon fired on the United States embassy in the Yemeni capital Sanaa on Tuesday, before he was himself shot and wounded by police and arrested, police said.
The gunman, whose identity has not been disclosed, is now being grilled by the security authorities over the pre-dawn attack against the well-guarded embassy in the northeast of Sanaa.
A source at the embassy said staff was being given at least one day off because of the incident.
The attack came two days after a Yemeni security source said 22 suspected members of Al-Qaeda accused of plotting attacks on Western targets in the country were being questioned by a special anti-terrorist tribunal.
Since the September 11 attacks in the United States in 2001, Yemen has worked with Washington in its so-called "war on terror" to clamp down on suspected Al-Qaeda members.
Yemen, one of the poorest countries on the planet, is the ancestral homeland of Al-Qaeda leader Osama bin Laden.
In October 2000, 17 US sailors were killed when suicide bombers attacked the destroyer USS Cole off the port of Aden in an attack claimed by the network.
In September, suspected Islamic militants tried to storm the US embassy in the Syrian capital Damascus using two explosives-laden vehicles and improvised explosives.