The 28-year-old, who had recently been fired from postage meter company Pitney Bowes, reportedly called himself the "Joker" and vowed to "blow everybody up." NBC's Brian Williams reports.

Updated at 6:37 p.m. ET: Police detained a Maryland man and recovered numerous guns from a home Thursday night after he allegedly made threats referring to the Joker this week.

Pat Collins of NBC Washington and Michael Kosnar of NBC News contributed to this report by M. Alex Johnson of NBC News. Follow M. Alex Johnson on Twitter and Facebook

Julie Parker, a spokeswoman for the Prince George's County police, said Friday that authorities had "thwarted a terrorist threat."

Prince George's County Police Chief Mark Magaw said the man, whom authorities identified as Neil Edwin Prescott, 28, of Crofton, Md., made a threat toward his employer, Pitney Bowes, in two phone calls to his supervisor Monday. Prescott was upset about losing his job and said: "I am the real Joker, and I'm going to blow everyone up," McGaw said.

Prescott was fired from his job as a subcontractor at Pitney Bowes, an office supply company, on an unrelated matter, the company said.

A Maryland man is accused of plotting an attack on his workplace using a weapons cache that was uncovered by authorities. NBC News' Chris Clackum reports.

Magaw said police took the threats very seriously "in light of what happened in Aurora" — a reference to the shooting deaths last week of 12 people in Aurora, Colo., at a screening of "Batman: The Dark Knight Rises." The suspect in that shooting, James Eagan Holmes, reportedly told police "I am the Joker" after he was arrested.

Prince George's County Police Authorities display the cache of weapons found in Neil Edwin Prescott's home.

A police database showed that Prescott had 13 guns registered in his name. Officers from the Anne Arundel County police, the Prince George's County police and the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives obtained a warrant and searched his home in Crofton, about 25 miles from Washington, on Thursday night.

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Ashan Benedict of the ATF's Baltimore division said at a news conference that investigators 25 firearms, including semiautomatic rifles and pistols, and several thousand rounds of ammunition from the home. Magaw said that when they arrived, Prescott was wearing a shirt that read, "Guns don't kill people, I do."

Police evacuated part of the apartment building and took Prescott into custody without incident, they said. He hasn't been charged and was undergoing a medical evaluation Friday at the Anne Arundel County Medical Center.

Authorities detailed the weaponry in Prescott's home in their search warrant:

4 30-round magazines

2 shotguns

1 Beretta .40-cal handgun

1 Ruger .45-cal handgun

2 KAHR 9mm handguns

1 Beretta 9mm handgun

2 Sig Sauer P226 handguns

1 Browning Arms handgun

2 Mauser rifles

1 FN Herstal rifle

1 Ruger 357 handgun

1 Night scope

100 rounds 12 remington

40 large steel boxes of ammo of various calibers

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