An investigation is underway after someone called in a bomb threat to the Walter Reed National Military Medical Center in Bethesda, Md., on Wednesday morning.
A Walter Reed spokesperson said someone called the center at 8:50 a.m. ET and said something was going to explode at 10 a.m. The center's Building 19, known as the America building, was evacuated and explosive detection dogs were brought in.
Authorities did not find a bomb in the first search of the building, which is for outpatient services. A Navy official said a second search was conducted as an extra precaution.
The center was given the "all clear" at 12:50 p.m. Medical appointments resumed at 1:00 p.m.
No information is available about the person who called in the threat, Reuters reported.
Walter Reed is among the nation's largest military medical centers, and last year the facility made the move from Washington, D.C. to nearby Bethesda, Md. After operating for more than a century, the center is expected to close for good.
NBC News' Courtney Kube and Reuters contributed to this report.
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