WASHINGTON — A Fairfax County, Virginia drain inspector stumbled upon an interesting find Tuesday — a more than 50-year-old explosive.

Fairfax County police received a call around 10:45 a.m. from a drain inspector who found an “unusual device” in a storm drain in the 9300 block of Glenbrook Road in the Mantua neighborhood. The device was later determined to be an inactive bazooka round from the Korean War era.

Police alerted neighbors and kept them at a safe distance while authorities investigated.

Police say they do not know how it ended up in the storm drain or how long it had been there.