Ball State University lifted a warning to shelter in place on Friday evening after a three-hour police search prompted by an individual shouting "gun" turned up no evidence of a gunman on the Muncie, Indiana, campus.
"The all clear has been issued," the university said on its website. "Campus is secure. Resume normal activities."
In a posting on its website earlier on Friday, the school told people to secure themselves in a safe location after "an individual in the recreation and wellness building shouted that there was a gun."
"They did two searches of the building and found no evidence of a gunman," said Tom Taylor, university vice president for enrollment, marketing and communications.
Taylor said in a telephone interview that police were not able to determine who shouted "gun gun gun."
Indianapolis television station WTHR showed aerial video of more than a dozen police cars with lights flashing at a campus intersection and amateur video of police officers searching the area.
An explosion heard on campus was determined to be an accidentally discharged service weapon outside the secured perimeter of the scene, the school said on its website.
About 21,000 students are enrolled at Ball State, which is located about 60 miles northeast of Indianapolis.
(Reporting by Brendan O'Brien in Milwaukee, Wisconsin; Additional reporting by Alex Dobuzinskis in Los Angeles; Writing by Scott Malone; Editing by Barbara Goldberg, David Gregorio, Lisa Shumaker and Mohammad Zargham)