An air force base northeast of San Francisco was locked down Wednesday in response to what authorities called a security incident, The Associated Press reported.
Travis Air Force Base issued a security alert at about 3:30 p.m. Officials asked people to shelter in place and lock doors and windows, the AP said.
Officials were investigating and did not know what was going on, a civilian who answered the phone at the base’s public affairs office told the wire service.
The lockdown came the same day that the base had been planning security lockdown exercises. However, officials said the incident was real and not a drill.