Security officials say Shiite rebels have reached a suburb of Yemen's capital where they are fighting Sunni militias and besieging a university run by one of the nation's best known Sunni radicals.

The officials say Thursday's fighting in Shamlan has forced thousands to flee their homes, but they have no word on casualties. They say the rebels, known as Hawthis, are surrounding the Iman University, an institution long viewed as a primary breeding ground for militants.

They say 60 people have been killed in the fighting during the last 48 hours.

The Hawthis have recently routed their rivals, expanding the area under their control in northern Yemen.

The officials spoke on condition of anonymity because they were not authorized to speak to the press.