ABC News has learned the raid was launched after U.S. intelligence received tips and examined Predator reconnaissance indicating that al Qaeda's No. 2 man may have been staying at the school, which is located in the Bajaur region near the village that is thought to be al Qaeda's winter headquarters.
Despite earlier reports that the missiles had been launched by Pakistani military helicopters, Pakistani intelligence sources now tell ABC News that the missiles were fired from a U.S. Predator drone plane.
THE BLOTTER RECOMMENDS
Between two and five senior al Qaeda militants were killed in the attack, including the mastermind of the airliners plot in the U.K., according to Pakistani intelligence sources.
No word yet on whether or not Zawahiri was killed in the raid, but one Pakistani intelligence source did express doubt that Zawahiri would have been staying in a madrassa, which is an obvious target for strikes against militants. That source, however, did express confidence that Pakistani intelligence is closing in on Zawahiri's location.
One of the clerics who is believed to have been killed today, Maulana Liaquat, was one of the two main local leaders believed to be protecting Zawahiri.
Pakistani intelligence sources tell ABC News they believe they have "boxed" Zawahiri in a 40-square-mile area between the Khalozai Valley in Bajaur and the village of Pashat in Kunar, Afghanistan. They hope to capture or kill him in the next few months.
Alexis Debat is an ABC News consultant.