The University of Oklahoma said on Wednesday it had found no evidence of shots being fired on campus or any sign of injuries related to a shooting, shortly after ordering a campus-wide lockdown.
The university said on its Twitter feed that police were continuing to search around Gould Hall, where the reports had been received, but normal operations had resumed everywhere else on its campus in Norman.
Dozens of emergency vehicles were on the campus, according to live video footage provided by a local broadcaster.
The incident came just a day after a man was shot to death at Indiana's Purdue University and amid heightened concerns over a rash of shootings at U.S. schools in recent weeks.
The frequency of shootings at schools and universities in the United States is fueling the national debate over gun control. On Monday night, a student was shot and critically wounded outside an athletic center at Widener University in Chester, Pennsylvania, near Philadelphia.
The University of Oklahoma, founded in 1890, has an enrollment of roughly 30,000 students.