A Long Island man was arrested on weapons charges on Thursday after police officers found assault rifles, bomb-making instructions, over $40,000 in cash and Nazi paraphernalia in his house, the authorities said.

The man, Edward Perkowski, 29, of Mount Sinai, also faces drug charges after the police recovered marijuana and mushrooms during the search.

Perkowski’s brother, Sean, 25, who also lives in the home, was arrested on an unrelated outstanding bench warrant, the police said.

“Today’s search warrant might have prevented a deadly, violent incident, like the one we recently saw in Orlando,” the Suffolk County police commissioner, Timothy D. Sini, said at a news conference in Yaphank.

Among the items the police found when they entered Mr. Perkowski’s house around 6 a.m. on Thursday was a black binder filled with instructions on bomb making, some handwritten. Six assault rifles, a handgun, a shotgun, four rifles and a stun gun, were also found, Mr. Sini said.

In a photo taken by the police at the house, a framed picture of Adolf Hitler rests next to a lineup of assault rifles.

“We neutralized a clear public threat,” Mr. Sini said.

John Leonard, who said he lives on the same street as Mr. Perkowski, said the police were frequently at the home.

“There’s been trouble at the house for a long time,” Mr. Leonard said before the news conference.

The Brookhaven town supervisor, Edward P. Romaine, said the house was infected with the “disease called hate.”

“And we want to stop hate in this country,” he said. “There’s enough.”

(The New York Times)