A gunshot scare that resulted in a lockdown at Walter Reed National Medical Center has been determined to be a false alarm — the second such incident in the past week in the Washington D.C. region.

The all-clear was given for the U.S. military hospital complex located in Bethesda, Md., after everyone inside was ordered to shelter in place while police combed the 20-story building with dogs, eventually finding that no shots had been fired and it was a false alarm, according to an Agence France-Presse report.

Officers investigated the person who made the initial call, who told police that they heard noise that could have been shots, prompting fears of an active shooter and resulting in a “code white” lockdown at the facility, where 7,000 people work and security is extremely tight.

It was the second false alarm for the D.C. region, the first being a similar incorrect report of a gunman at the Washington Navy Yard in D.C. That was a particularly scary report as the Navy Yard had been the scene of a mass shooting in 2013 when a lone gunman slaughtered 12 people.

Walter Reed National Military Medical Center, formerly known as the National Naval Medical Center and often referred to as the Bethesda Naval Hospital, is located near the National Institutes of Health and is considered one of the most prominent military medical centers in the D.C. region, and the entire United States. It has served numerous U.S. presidents ever since being founded in 1940, including President Barack Obama.