A suspect plotted to place at least seven improvised explosives across New York City, including on a subway track on the Williamsburg Bridge and a Manhattan apartment rooftop, according to law enforcement.

Michael Gann, 55, of New York City, allegedly ordered chemicals that can be combined to make explosives, built seven devices and placed six of them before he was stopped by law enforcement.

According to the indictment, Gann’s alleged bombs were far more powerful than any legally-obtainable consumer explosive, containing “approximately 30 grams of explosive powder, which is approximately 600 times the legal limit for consumer fireworks.”

Police allegedly captured Gann placing his devices on rooftops via surveillance footage.

He’s being charged with one count of attempted destruction of property by means of explosives, one count of transportation of explosive materials, and one count of unlawful possession of destructive devices.

If convicted, Gann will face a maximum penalty of 40 years in prison.