A member of a worldwide computer-hacking group pleaded guilty in Los Angeles Monday to federal charges of making bogus shooting and bombing threats against schools both abroad and domestically, including some in Southern California.

Timothy Dalton Vaughn, 21, of North Carolina, pleaded guilty to conspiring to make threats and damage a computer, computer hacking and possession of child pornography. In his online dealings, Vaughn went by names like “WantedbyFeds” and “Hacker_R_US,” authorities said.

According to his plea agreement, Vaughn admitted providing a co-defendant with contact information for at least 86 school districts that later received emailed threats of an armed student, imminent detonation of bombs or the placement of explosives under school buses or on athletic fields.

He also admitted to a 2018 computer-hacking ransom attack on Hoonigan, a Long Beach motorsports company. Vaughn threatened to take down Hoonigan’s website unless the company paid him $20,000 worth of bitcoin, according to the plea agreement.

“This is not a joke and this is to be taken seriously,” the threat said. “You can Proudly Direct Message me When you have paid on Twitter @WantedbyFeds Or When i completely receive payment i will see it and stop the attacks (sic).”

Vaughn also threatened to release all of Hoonigan’s customer information, according to an indictment.

“When the company refused to pay, he launched a DDoS attack that disabled hoonigan.com,” authorities said.

The attacks cost Hoonigan $5,000. Later, Vaughn  bragged in a chatroom that he had crippled the business, according to the indictment.

The U.S. Attorney’s Office said, Vaughn also admitted helping a co-defendant make a bogus threat of a hijacking on a United Airlines plane flying from London to San Francisco, and admitted possessing nearly 200 sexually explicit photos and videos of children.

Vaughn faces up to 35 years in prison when he is sentenced June 8.

The co-defendant involved in the bogus hijacking threat—20-year-old George Duke-Cohan of the United Kingdom—is serving prison time in Britain. He is charged with nine more counts in the Los Angeles case.

Valerie Osier and Jeremiah Dobruck contributed to this report.