ORANGE PARK, Fla. – A 20-year-old Clay County man was arrested Thursday, accused by the U.S. Attorney's Office of instructing someone how to make a pressure-cooker bomb, fill it with nails, metal and other items dipped in rat poison to disrupt a Sept. 11 memorial event in Kansas City.

After an undercover investigation, the FBI arrested Joshua Goldberg on charges of distributing information related to explosives and weapons of mass destruction. He faced a judge at the federal courthouse in Jacksonville on Thursday.

According to U.S. Attorney Lee Bentley III, Goldberg instructed a confidential source how to make a bomb similar to two used in the Boston Marathon bombings two years ago that killed that killed three people and injured an estimated 264 others.

CRIMINAL COMPLAINT:

Arrest of Joshua Goldberg

In online conversations with the undercover informant, Goldberg is accused of expressing hope that "there will be some jihad on the anniversary of 9/11."

When the informant expressed a desire to assist in an attack, Goldberg -- who was living at home with his parents at the time -- is accused of providing detailed and credible information on how to go about constructing the bomb.

According to court documents, the FBI traced Internet communications to Goldberg, who claims he was the person who motivated two men to attack the cartoon convention in Garland, Texas, in June because they were going to depict the Muslim Prophet Mohammad. Two people died in that attack.

The arrest came after an investigation that included the FBI, the Clay County Sheriff's Office, NCIS, Immigration and Customs Enforcement, U.S. Customs and Border Protection, the Florida Department of Law Enforcement and the Jacksonville and St. Johns County sheriff's offices.

News4Jax spoke with Goldberg's family, who said they had no idea anything was going on.

Neighbors also told News4Jax the FBI swarmed their very quiet neighborhood early Thursday morning. And apparently no one had any idea anything was wrong inside the home.

News4Jax went to Goldberg's address and heard numerous children inside the residence, then spoke with Frank Goldberg, who said he is Joshua Goldberg's father.

"I'm with Channel 4," News4Jax reporter Scott Johnson said to Frank Goldberg.

"We really don't want to talk about anything right now," Frank Goldberg said. "We don't have any more information at this point."

"Did you know anything about this?" News4Jax asked.

"Not until today," Frank Goldberg said. "I appreciate you -- another time we would like to talk to you, but there hasn't even been an initial hearing yet, so we have no idea what was going on. We had no idea."

The report from the U.S. Attorney's Office shows Goldberg used the Twitter handle AusWitness. An exchange between AusWitness and a confidential source was made public.

"Have you decided what kind of attack to carry out on 9/11, akhi?" AusWitness tweeted.

"I was thinking a bombing," the confidential source replied.

"We could make pipe bombs and detonate them at a large public event," read the tweet AusWitness posted that officials believe was the plan for an event in Kansas City, Missouri.

They then talk about how to make a pressure cooker bomb.

"Don't buy all the materials at once or the kuffar will know you're up to something. Buy them at different stores," AusWitness tweeted.

Neighbors in the Clay County neighborhood where Goldberg lives said they are simply stunned.

"Are you kidding?" Ed Saple said. "Boy, you never know where it's safe, do you? This is a very quiet and safe neighborhood."

News4Jax spoke with Ronald, who didn't want to give his last name, who said his grandson would play with children at the house.

"What do you think I think of it? It's crazy. Obviously the guy's not right in the head. He stayed upstairs in the back bedroom, he never knew the guy lived there," Ronald said.

Ronald said one of his family members noticed something was wrong when the FBI swarmed the house early Thursday morning.

"When she came up they had the SWAT team and everyone in their riot gear and all that," said Ronald.

One interesting thing that neighbors said is that they never knew Joshua Goldberg lived there and said he stayed in a back room and never came out. In fact, the FBI put the house under surveillance on Aug. 20, and it took a long time before they even saw him come outside.