Planned Massacre Foiled By Maryland Cops

One week after Colorado's movie theater shooting, Maryland cops arrested a heavily armed man who told his employer he was a "joker" who was going to "blow everyone up."

Police said today they believe they "thwarted a massacre."

The suspect was being dismissed from his job and twice gave threatening statements to his supervisor, police said.

He was quoted as telling his employer, "I'm a joker, I'm going to load up my guns and blow everyone up," police said.

Law enforcement sources tell ABC News that he is from Crofton, Md. He is under arrest for allegedly making threats against an employer and co-workers at Pitney Bowes.

The suspect had about 25 firearms at his residence, including semi-automatic rifles, shotguns and handguns, law enforcement sources said. Police also said he had thousands of rounds of ammunition.

The man was facing termination from his job with a company doing contract work for Pitney Bowes, a leading company in producing postage meters and machines.

The company released the following statement: "The suspect arrested is an employee of a subcontractor to Pitney Bowes. At Pitney Bowes we have clear security protocol and when we had concerns about this individual, we contacted authorities."

The Prince George Police Department declined to comment, but said they will be sharing more information at a 1 p.m. news conference.

On July 20, shooting suspect James Holmes allegedly opened fire in an Aurora, Colo., movie theater during a midnight showing of the new Batman movie, "The Dark Knight Rises." Twelve people were killed and 58 were wounded.

Holmes told police he was The Joker, a villain in the Batman movies, police said.