SEOUL: A major US air force base in South Korea went into full lockdown for more than an hour on Monday after what appeared to be a false alarm about a shooter at the facility’s high school. “The security forces sweeps are now complete. There were no reported injuries or suspicious activity found,” the 51st Fighter Wing stationed at Osan Air Base said in a post on its official Facebook page. “Everyone is safe. The lockdown has been lifted,” it added. Osan Air Base is located some 65 miles south of Seoul and hosts 28,500 US military personnel permanently based in South Korea.