Two U.S. aid workers, a husband and wife, were attacked and beaten by a mob of students in a predominantly Christian part of southern Sudan. The reasons for the attack are still unclear, but the aid organization for which they work said the two Americans were targeted during a student protest against a local school. Aya Batrawy has more from our Middle East bureau in Cairo.

The U.S. aid workers were attacked and beaten by a mob of students in the town of Julud in southern Sudan. The students attacked the aid workers and ransacked their office over the weekend. The U.S.-based Samaritan's Purse Ministry, the aid workers' employer, said Sudanese students were likely protesting against rising tuition fees.

Jeremy Blume, of Samaritan's Purse, an Evangelical Christian organization, said students attacked the aid workers in an isolated incident that was not directly aimed at the organization or its work.

"We're helping out in the area with food assistance, medical programs, church rebuilding in southern Sudan," he said. "It seems the students were just reacting to some changes there at the school and reacted against our team."

Over two million people were killed and many villages destroyed during the 20-year civil war between Sudan's Muslim north and the Christian south.

The peace agreement reached in 2005 has not guaranteed an end to violence in Sudan.  Aid workers and people living in southern Sudan continue to face insecurity as they try to rebuild villages destroyed during the war

Blume said the incident, although isolated, is not the first time the evangelical group's workers in southern Sudan have come under attack.

"Our hospital there has been bombed more than seven or eight times over the past six or seven years," he said. "It's part of the danger of working in this country, but we have a passion for people, and there are a lot of things we can do to help so we're going to stay."

The aid organization said Sudanese authorities have detained a number of people in connection with the incident.