One person was airlifted to a North Carolina hospital Thursday after receiving life-threatening injuries from an apparent manhole explosion on University of North Carolina's Charlotte campus, officials told FOX News.

Three other people were taken by ground transportation to a local hospital; all four of the victims are staff members at the university.

Classes were cancelled on campus because of a power outage that workers were investigating underground when the manhole exploded around 7 a.m. EDT near the campus' main entrance.

The explosion happened near the Fretwell Building, which was evacuated and is reportedly filled with heavy smoke, officials said.