SEOUL - The US Osan Air Force base in South Korea went into lockdown Monday after reports of a possible shooter at a high school on the site, although the principal suggested it may be a false alarm.
"We have received reports of a possible active shooter incident," the 51st Fighter Wing based at Osan said in a post on its official Facebook page.
"A perimeter has been established and security forces are sweeping the area," the post said.
Osan Air Base, some 65 miles south of Seoul, is one of a number of facilities housing the 28,500 US military personnel permanently based in South Korea.
A statement from the principal of the school, Morgan Nugent, suggested the lockdown had been a precautionary reaction to a possible hoax call.
"One of our teachers received a call that sounded automated saying that there was an active shooter drill taking place," Nugent said.
"There was no scheduled school shooter drill on base, so we have decided to err on the side of safety and went into a full school lockdown," he said.
"Once we are given an all clear we will go ahead and continue the school day," he added.
The 51st Fighter Wing said the lockdown had been extended to the entire base, and added that a complete security sweep would be conducted before signalling the all-clear.