SAN’A, Yemen — Yemeni police have arrested five suspects in a mortar attack that American officials say targeted the American Embassy but instead struck a girl’s high school next door, an Interior Ministry official said today.

The three mortar rounds, which killed a Yemeni guard and wounded more than a dozen girls, appeared to have been fired Tuesday from the rooftop of a nearby building rented by the attackers, the ministry official said. He spoke on the condition of anonymity because he was not authorized to speak to the press.

The official gave no further details about the attackers, their identities or their motivation for the attack.

The shells fired in the downtown San’a district of Sawan wounded five soldiers and 13 girls, three of them seriously.

The State Department said Tuesday that embassy officials concluded the attack was directed at the embassy. Washington “will be looking to work with Yemeni authorities as they investigate this incident,” a State Department spokesman, Tom Casey, said.

The embassy has informed its nonessential staff they will be permitted to leave Yemen, a spokesman, Ryan Gliha, said. The embassy said it will provide free flights to staff members unwilling to remain.

The Interior Ministry official initially suggested the attack might be linked to a dispute between a teacher and school administrators. The school had received a warning two days earlier from the teacher’s family, the official said.

Al Qaeda has an active presence in Yemen despite government efforts to destroy it. The group was blamed for the 2000 bombing of the USS Cole destroyer in the Yemeni port of Aden that killed 17 American sailors and an attack on a French oil tanker that killed one person two years later.