In a complaint filed Monday, the FBI charged Boardman, Ohio resident Justin Olsen with threatening to assault a federal law enforcement officer after he posted on an online forum: "In conclusion, shoot every federal agent on sight".
The 18-year-old's account on the iFunny website, a forum where users share memes had approximately 4,400 subscribers.
He had previously made posts supporting mass shootings and targeting family planning and reproductive rights group Planned Parenthood, the complaint said.
After searching his father's house, agents found around 15 assault rifles and shotguns and 10 semi-automatic pistols inside the bedroom of Olsen's father, along with the ammunition.
Agents also found "camouflage clothing and camouflaged backpacks," according to the complaint.
Olsen admitted to making the online comments, the complaint said, but insisted they were "only a joke" and were made in regards to the controversial 1993 standoff in Waco, Texas.
The Branch Davidians religious sect held off federal authorities attempting to arrest their members on weapons charges until theFBI eventually launched an assault and used tear gas.
A fire engulfed the sect's compound and 76 people died
Olsen's arrest came a week after back-to-back massacres killed 31 people in El Paso, Texas and Dayton, Ohio, sparking calls for lawmakers to limit the availability of firearms and reduce the carnage from gun violence in the United States.
In a complaint filed Monday, the FBI charged Boardman, Ohio resident Justin Olsen with threatening to assault a federal law enforcement officer after he posted on an online forum: 'In conclusion, shoot every federal agent on sight.'