PALMER PARK, Md. — A Maryland man who called himself “a joker” and had an arsenal of semi-automatic rifles threatened to shoot up the business from which he was being fired and was wearing a T-shirt that read “Guns don’t kill people. I do,” when first confronted by officers, police said today.

The man, identified in a search warrant as Neil E. Prescott, told a supervisor at software and mailroom supplier Pitney Bowes that, “I’m a joker and I’m gonna load my guns and blow everybody up,” and that he wanted to see the supervisor’s “brain splatter all over the sidewalk,” according to a police officials and a search warrant.

The threats were made two times in separate phone calls this week, and investigators who searched the 28-year-old’s apartment this morning found several thousand rounds of ammunition and about two dozen semi-automatic rifles and pistols. He was receiving a psychiatric evaluation at a hospital and charges were pending today.

“We can’t measure what was prevented here, but was going on over the last 36 hours was a significant incident in the county. And we think a violent episode was avoided,” said Prince George’s County Police Chief Mark Magaw. The workplace that Prescott is accused of threatening to shoot up is located in the county, just outside Washington.

It wasn’t immediately clear when the threat was to be carried out or how seriously it was meant to be taken, but last week’s mass shooting at a Colorado theater during the latest Batman movie — coupled with the “Joker” reference — put police especially on edge and gave the comments extra urgency, officials said.

“In light of what happened a week ago in Aurora Colo., it’s important to know, (for) the community to know, that we take all threats seriously. And if you’re going to make a threat, we will take action,” Magaw said.

Though there’s no other indication of a link to the Colorado shooting, police think the joker comments Prescott made were a “clear reference” to the killings, the warrant says. The man accused in those shootings, James Holmes, had his hair dyed reddish-orange as if out of a comic book, and New York Police Commissioner Ray Kelly has said he also called himself the Joker, though Aurora police have not confirmed that.

It was not immediately clear if Prescott had a lawyer. The only other prior contact he’s appeared to have with Maryland police was a 2007 speeding ticket in Anne Arundel County.

Neighbor Wilbert Brinson, who lives in a building across from Prescott’s but did not know him, said he was alarmed by the alleged threats.

“It’s an awakening, you know, after hearing what happened in Colorado,” he said.

Police would not confirm Prescott’s identify today because charges are pending. He was receiving an emergency mental health evaluation at a hospital and was taken into custody this morning at his apartment in Crofton, near Annapolis, after a supervisor reported the threat to the police. Police on Thursday made an initial visit to Prescott’s home, where he appeared groggy and was wearing a T-shirt that said, “Guns don’t kill people. I do,” authorities said.

“The multiple threats and the nature of the threats and that action, together, led us to a place where we could get an emergency petition” for a psychiatric evaluation, said Deputy Police Chief Henry Stawinski.

According to the warrant, Prescott made the threat during a phone call on Monday morning when a supervisor contacted about him a work-related matter, then made similar statements in a separate conversation about 15 minutes later, and acknowledged, “It’s kind of foolish of me to say this kind of things over government phone.” The man who said he received the threat did not wish to speak about it, his son said

Police served the search warrant this morning and took him into custody without a struggle, police officials said.

Pitney Bowes spokeswoman Carol Wallace said in a statement that Prescott was an employee of a subcontractor to the company and had not been on any Pitney Bowes property in more than four months.

Associated Press writers Jessica Gresko and Brian Witte and AP researcher Judith Ausuebel contributed to this report. Zongker reported from Washington.