Bomb scares at two US universities led to thousands of students and staff being ordered off campus on Friday, though no explosive devices were found after the mass evacuations.
University of Texas and North Dakota State University received phoned-in bomb threats following which mass evacuations were ordered at the two Universities.
Scared students, anxious parents and officials were taken by surprise when the two universities received phoned-in bomb threats.
Thousands of students and faculty were asked to stay off campus or get away as soon as possible.
A man claiming to be with Al Qaeda called The University of Texas in Austin at 8:35 am (local time). He claimed that he had placed bombs all over the 50,000-student Austin campus, University of Texas spokeswoman Rhonda Weldon said.
He claimed the bombs would go off in 90 minutes and all buildings were evacuated at 9:50 am (local time) as a precaution, Weldon said.
North Dakota State University President Dean Bresciani said 20,000 people were evacuated from his school's main and downtown campuses in Fargo after the school received a bomb threat.
However, no bombs were found on either campus by early afternoon but it was not clear whether the threats were related.
The deadline passed without any incident, and the Texas University later issued advisories saying all buildings have been cleared and were reopening by noon.
Classes were cancelled for the remainder of the day, but other university activities were to resume by 5 pm (local time).
Officials did not immediately release details about the North Dakota threat and its evacuation remained in place by early afternoon.