The discovery shocked the neighborhood, with 20 homes evacuated as police cleared everyone out of a 500-foot possible explosive radius.
Investigators remained on the scene Wednesday.
It began when police responded to a silent alarm at a home on Narrow Lane. They found the 53-year-old son of an elderly couple inside and noticed the pungent odor of marijuana. They also say they spotted the grenades and a gun, which was enough for a warrant and a quick arrest of Marc Ringel.
A search by FBI and ATF agents ensued and uncovered 15 pipe bombs, 20 long guns, 50 pounds of ingredients to make explosives, 15 grenades and 100 handguns. A shallow pit in the backyard is believed to be a testing site to make explosives.
Police say Ringel grew up in Woodmere and attended Lawrence High School before moving to the midwest. He married and then divorced, and had reportedly been living at his parents' house on and off with and without their knowledge.
He also has a criminal background after he was apparently charged with criminal contempt of court in a domestic-related issue.
Authorities say they have no knowledge of him acting with terrorist group, but say the munitions were live and that there was enough explosives in the house to level the entire block.
They also say he had enough pot to have been selling it, and that he did not have a permit for any of his weapons.
Neighbors expressed concerns about what led to the arrest.
"He looked a little delirious," another said. "I only saw him for like a half a second. I didn't really want to look in the back of the cop car, but he definitely was not healthy looking."
Ringel is charged with weapons possession. Other charges are pending. He has been ordered to receive a psychological evaluation.
Ringel was walked into Nassau University Medical Center Wednesday and, for a man facing drug, weapons, and explosives charges, seemed more concerned about his parents.
LINK: VIEW PHOTOS OF WEAPONS
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