Omar Hammami - an American jihadist also known as Abu Mansour al-Amriki - was killed in fighting for the terror group al-Shabaab near Mogadishu, Somalia's Defense Minister said Tuesday. That report remains unconfirmed.

The announcement comes amid reports that al-Shabaab, al-Qaida's affiliate in Somalia, has suffered serious setbacks on the battlefield and could be on the verge of collapse. "We shall also sweep them away from Mogadishu. Our enemies have suffered a great loss; it is obvious they will run away from many towns," Somali President Sheikh Sharif Sheikh Ahmed told reporters Monday.

Somali witnesses told Reuters that al-Shabaab fighters had deserted a number of towns that had come under siege from advancing Ethiopian and Somali troops. Those troops captured numerous towns from al-Shabaab near the Ethiopian and Kenyan borders over the weekend. Somali President Ahmed said the Ethiopians were giving his forces logistical help. Kenyan authorities are attempting to capture fleeing al-Shabaab fighters that have crossed the border into that country.

It would be a major blow to al-Shabaab if Hammami, one of its senior commanders, is dead. Born near Mobile, Ala. 26 years ago, he grew up a Christian before converting to Islam and becoming president of the Muslim Students Association at the University of South Alabama at the time of 9/11. "Everyone was really shocked," he said at the time. "Even now it's difficult to believe a Muslim could have done this."

Hammami dropped out of school the following year and moved to Toronto two years later and arrived in Somalia in 2005, where he joined al-Shabaab and rose through the ranks. In September 2009, he was indicted on charges that included providing material support to terrorists and providing material support for al-Shabaab, a designated terrorist organization.