Twenty-eight students at the Mississippi University for Women sought treatment at a hospital because of high levels of carbon monoxide in their dormitory.
Kincannon Hall was evacuated early Tuesday after students started smelling natural gas.
Columbus Fire and Rescue spokesman Anthony Colom says first responders determined that a boiler in the basement was leaking. He says that filled all five floors of the dorm with high levels of carbon monoxide.
University spokeswoman Anika Perkins says all 28 students at Baptist Memorial Hospital-Golden Triangle were alert and responsive and says the university dean of students accompanied them. The dorm reopened by midmorning, and the students were all out of the hospital by midday.
Kincannon Hall is a freshman dorm at the university with 2,800 students.