TUCKAHOE, N.Y. (CBSNewYork) — Police say a prominent doctor had an arsenal of illegal assault weapons and firearms accessories in his possession.

He was being held without bail on Wednesday, accused of making some deadly plans, CBS2’s Tony Aiello reported.

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The array of weapons was found in the rear compartment of a luxury SUV, police said. The vehicle was driven by a prominent doctor, who allegedly told a friend he was thinking of committing a horrific act of violence.

At an upscale bar in Tuckahoe on Monday evening a man stepped outside and called police, warning them he was with a friend, plastic surgeon Dr. Matthew J. Bonanno, who showed him a gun and threatened his estranged wife.

(Photo: Tuckahoe Police Department)

“The threat was that he was going to kill his wife and her family,” Tuckahoe Police Chief John Costanzo said.

Officers arrived and said they found the following in the rear of Bonanno’s SUV: Smoke grenades, brass knuckles, body armor, 1,600 rounds of ammo, illegal high-capacity magazines and drums. Also found were rifles with banned features, such as detachable magazines in conjunction with, “a pistol grip, which by itself makes it an assault rifle. Plus a number of them had telescopic butt stocks, muzzle breaks,” Westchester County Assistant District Attorney Stephen Ronco said.

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Matthew Bonanno (credit: MJBonanno via Twitter)

Investigators said they found an equally large arsenal at Bonanno’s home on East Shore Road in the Nassau County town of Great Neck.

“We will find out how these guns came into the defendant’s possession, and why he had such an unusual collection of weapons in the vehicle, as well as other locations,” Westchester County District Attorney Anthony Scarpino said.

Bonanno is a former vice president of the prestigious New York County Medical Society. Prosecutors said he looks dramatically different than the photo provided to CBS2, having lost a lot of weight and grown a beard.

Police said the doctor’s friend who reported his concerns to them is a hero who may have prevented unimaginable violence.

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The doctor’s estranged wife lives in Tuckahoe. They have one child.