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(CNN) —  

Authorities have arrested an 18-year-old Ohio man who the FBI says threatened to assault federal law enforcement officers in an online post and showed support for mass shootings.

A criminal complaint alleges that Justin Olsen of Boardman, just south of Youngstown, discussed the 1993 Waco siege on iFunny, a mobile app for memes and funny images, in June.

He blamed the Bureau of Alcohol, Tobacco, Firearms and Explosives for the deaths of scores of people living at the site, the complaint filed by an FBI agent says.

“In conclusion, shoot every federal agent on sight,” Olsen wrote at the end of the discussion, the complaint says.

The FBI went to Olsen’s house last Wednesday, where they found 15 long guns, 10 pistols, about 10,000 rounds of ammunition and camouflage clothes.

Olsen waived a reading of the charges in court Monday. He was not asked to enter a plea and is scheduled to appear in court again in Friday for a bail hearing.

CNN has reached out to his attorney Ross T. Smith but hasn’t received a reply.

The criminal complaint said the investigation into Olsen began in February, when FBI agents in Alaska started looking into posts from user ArmyOfChrist that voiced support for mass shootings and the targeting of Planned Parenthood. Agents subpoenaed iFunny for information about the subscriber and received a Gmail address. The FBI subpoenaed Google, which they said linked the account to Olsen.

In the complaint, an FBI agent writes that Olsen said that his online comments were a joke and referred to it as a “hyperbolic conclusion based on the results of the Waco siege … where the ATF slaughtered families.”

In February 1993, four ATF agents were killed trying to serve a search-and-arrest warrant for illegal weapons at the Branch Davidian compound near Waco, Texas. Instead, a gun battle ensued.

The incident prompted a seven-week stalemate, eventually leading to a fire and the deaths of 76 Davidians, including their leader, David Koresh.