Eight sticks of military-grade explosives were found at the New York City Marble Cemetery in the East Village of Manhattan, the police commissioner said.
The explosives were dug up in May or June 2009 by a groundskeeper and laid away, Police Commissioner Ray Kelly told reporters. A volunteer cleaning within the cemetery found the bag.
The explosives were not set up or wired to set off.
Each stick is about one and a quarter pounds, said Kelly, who recognized the powerful explosive as C-4.
"Inside a building, clearly it could have caused an awful lot of damage," he said.
Kelly added the material would be taken to a police sacking range by members of a bomb squad.