Students and professors hunkered down around noon on Wednesday, as police checked out a call of someone firing shots on campus.
Students got the all clear within the hour when they realized it was a false alarm.
It seems to have been backfires from construction equipment that prompted the emergency. But it still gave police a chance to practice their shooting response plan.
OU students were told to, "shelter in place," after a reported shooting at Gould Hall, the home of the College of Architecture. It's on the south end of campus near the football stadium and Gaylord Hall.
Campus and Norman police responded in force and set up a perimeter around Gould Hall.
Less than 45 minutes later, students were given the "all clear." OU President David Boren said a faculty member reported hearing three shots, but they were apparently back-fires from construction equipment.
Gould Hall reopened after a second sweep by police.
Boren says the University's emergency response worked as planned.
Some nearby Norman Public School buildings were also briefly locked-down, but they re-opened within an hour, too.