Air Force Academy officials are looking into how a report of an active shooter got started on base late Friday night.

The report was ultimately determined to be unfounded, according to officials. No evidence of shots fired was ever found.

The ordeal began around 9:45 p.m. after the El Paso County Sheriff's Office received calls about gunshots heard on the campus, specifically in the area of the prep school. An alert was sent out to academy personnel and cadets a short time later placing the campus on lockdown while security forces and other law enforcement swept every building. A number of people who had just been on academy grounds for a high school football match between Air Academy and Sand Creek found themselves trapped on base until the gates reopened early Saturday morning.

During the sweep, rumors circulated about the number of shooters and their tactics, but law enforcement stressed later that the rumors were baseless.

"There were reports of an active shooter. That's all we know. But there was determined that there was no active shooter and that there were not shots fired and no injuries," Lt. Col. Allen Herritage told 11 News after the situation concluded.

Officials are now investigating whether the shots-fired report originated as a misunderstanding, such as confusion over a loud noise, or if it was a deliberately false report.

The whole thing may have been inadvertently caused by a nerf gun battle at the prep school. Our partners at The Gazette say several sources told them a couple of people mistook the innocent fun as real-life danger and called 911. 11 News received a similar tip from an anonymous parent, who also cited the nerf gun war and said they believed that may have been what the initial 911 caller was hearing.

A Snapchat video purporting to have been taken on the AFA late Friday night does show students darting around a stairwell pelting each other with nerf guns.

This has not been confirmed publicly by the academy, who have said they are still looking into the incident.

"The academy officials will continue to investigate the situation to determine the source for these allegations, but for now, everyone is safe and the academy is all clear," Herritage said.

UPDATE (1:30 a.m.): Everything is clear and everyone is okay at the US Air Force Academy (Official). There is no active shooter and the gates are back open. Officials are looking into what caused the reports of an active shooter. http://www.kktv.com/content/news/BREAKING-Reported-active-shooter-at-the-United-States-Air-Force-Academy-448771323.html Posted by KKTV 11 News on Saturday, September 30, 2017