A Yemeni guard was killed in an explosion Tuesday near the US embassy in the capital of San'a, a Yemeni Interior Ministry official said. Other local guards and some schoolchildren were also wounded in the blast. The official spoke on condition of anonymity as Yemeni officials often do, according to protocol. The official said the blast came after unknown attackers fired a mortar at a high school next to the American embassy in the downtown San'a district of Sawan. He said three guards and three children were wounded. However, it remained unclear if the embassy or the school was the target.