FALLS CHURCH, Va. (AP) — A report of an active shooter in the Skyline section of Fairfax County prompted a massive police response and brief lock-in of two schools, but it was all a false alarm.

Fairfax County Police spokesman Don Gotthardt said police received a call Thursday afternoon about a possible active shooter at 5109 Leesburg Pike, which is home to federal tenants and private offices.

Police alerted the public through Twitter and began searching the building. Gotthardt said police learned during the search that somebody was running a drill. He said it remains unclear who was running the drill. He also said somebody may have misunderstood a message about an upcoming drill.

In nearby Arlington County, Wakefield High School and Claremont Immersion school briefly locked their doors as a result of the scare.