The bomb squad was removing the bag of C-4, a military-grade plastic explosive that is more powerful than TNT. C-4 requires a detonator, or cap, to explode and police said no caps were found at the scene.
It wasn't immediately clear who put the bag in the East Village burial ground. Police were called to the scene around 10:45 a.m., and the streets nearby were closed.
There are two cemeteries side-by-side, both called Marble and both considered historic. It's not clear which cemetery the bag was placed in. One was designated a landmark in the late 1960s. Six members of a branch of the Roosevelt family are buried there, as well as a Stephen Allen, former mayor and New York governor.