Federal agents found one of the largest stockpiles of homemade explosives they have ever seized when they arrested a Virginia man on a firearms charge last month, according to a court filing by federal prosecutors.

Prosecutors are fighting to keep a Virginia man behind bars after they say investigators found what could be the largest number of “finished explosive devices” in FBI history at his 20-acre home near Norfolk.

The FBI is working to determine the plans of a 36-year-old suspect after investigators discovered over 150 explosives, primarily pipe bombs, on his 20-acre farm. According to the FBI, this is the largest cache of explosives ever found in the bureau’s more than 100-year history.