A man arrested in Ohio for threatening a Jewish community center on Instagram is an avowed white nationalist and had an arsenal of firearms and combat gear in his home when he was taken into custody, police said.

James Reardon Jr., 20, was arrested by New Middletown Police on Saturday and faces charges of menacing and harassing. He's being held on $250,000 bond in Mahoning County Jail and is scheduled to appear in court Monday.

Vincent D'Egidio, the police chief in New Middletown, told CBS affiliate WKBN-TV officers on Friday got a tip about the video, which shows a man who appears to be Reardon firing a semi-automatic rifle.

Get Breaking News Delivered to Your Inbox

The caption on the post, which appeared on the account @ira_sheamus, reads, "Police identified the Youngstown Jewish Family Community shooter as local white nationalist Seamus O'Rearedon." "Seamus" is the Gaelic equivalent of "James." The user tagged the Youngstown center in the post, which was dated July 11.

"That kicked off an intense investigation, a very rapidly evolving investigation because of the way the world is," D'Egidio said. He said his officers ramped up protection at the community center and the department contacted the FBI.

On Friday, the FBI's Violent Crimes Task Force obtained a warrant and raided Reardon's home, WKBN-TV reports. Officers seized several weapons, a gas mask, body armor and dozens of rounds of ammunition, as well as anti-Semitic and white nationalist propaganda.

A photograph of some of the guns James Reardon Jr. owned. Reardon allegedly threatened on social media to shoot-up a Youngtown, Ohio Jewish Community Center. CBS/WKBN-TV

It was not immediately clear whether the FBI and federal prosecutors would pursue additional charges against Reardon. A New Middletown officer said the bureau would be releasing a statement Sunday afternoon about the case. It was not immediately clear whether Reardon had an attorney.

Reardon attended the violent white nationalist protests in Charlottesville, Virginia in 2017 and appeared in a documentary in which he espoused white supremacist views, according to WKBN-TV.

"This is a person that has declared himself as a white nationalist. With the hate crimes and everything else going on, we want to make sure we did our part to make sure this person was taken off the streets very quickly," D'Egidio said.

On Saturday, the Anti-Defamation League's Cleveland chapter thanked law enforcement for their work on the case.

"Grateful for the work of the FBI, local law enforcement and our community partners in the Youngstown Jewish community," the group said on Twitter. "We will continue to employ all our resources to stop the spread of white nationalism and violent extremism."