The university said it was providing food and counseling for the evacuated students at its Veterans Academic Resource Center. Tower 1 reopened later Monday.
Firearms are prohibited at UCF, which is home to about 59,000 students at its main Orlando campus and 10 regional facilities.
As the evacuated students waited for hours to return to their building, worst-case scenarios raced through their heads.
"He was just above us," Graham said. "What if the roof caved in because a bomb went off and everyone in the building got hurt? That's just the crazy part."