Security officials and witnesses in the southern Yemeni city of Aden say militants have bombed a local college, following previous threats against the school.

The officials said militants on a motorcycle tossed a bomb Wednesday onto the sprawling campus of the University of Aden. It shattered windows at the College of Commerce and Economics. Terrified students ran for safety.

There was no immediate word on casualties or a claim of responsibility.

A university official has told the AP that Islamic militants had vowed to attack the school if it did not gender-segregate classes.

Yemen is torn by fighting between the government and Shiite rebels, with Islamic extremists exploiting the chaos.

Officials and witnesses spoke on condition of anonymity because they are not authorized to brief reporters or fear reprisals.