Police in Ohio arrested a white nationalist for allegedly threatening to shoot up a Jewish community center in an Instagram video — and seized an arsenal of weapons from his mother’s home that included two AR-15-style rifles, bulletproof armor and a ton of ammunition.

James Patrick Reardon, 20, was charged Saturday with telecommunications harassment and aggravated menacing for allegedly posting a chilling clip of a man firing multiple rounds from a rifle in the dark, as sirens and screams can be heard in the background, WYTV reported.

The post tagged the Jewish Community Center of Youngstown and the caption read: “Police identified the Youngstown Jewish Family Community shooter as local white nationalist Seamus O’Reardon.”

That name was a pseudonym Reardon used online, New Middletown police said.

“He was implying that he was going to be identified as the shooter of the Jewish Center,” Police Chief Vince D’egidio told WFMJ.

The FBI Violent Crimes Task Force raided Reardon’s mother’s home Friday and police seized a cache of weapons, including the two semi-automatic rifles, a rifle with a bayonet, a .40-caliber anti-tank gun, knives, several magazines, 223 rounds of ammunition, a gas mask and a bulletproof vest.

A Confederate flag flask and a jacket with Irish Republican Army patches on it were also seized.

D’egidio said “there were several videos that [Reardon] posted on Instagram where he used a lot of derogatory remarks towards the Jewish community and the African American community.”

“This is a person that has declared himself as a white nationalist,” D’egidio added. “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.”

Reardon was at the 2017 white supremacist rally in Charlottesville, Va., where a neo-Nazi drove into a crowd of protesters, killing a 32-year-old woman and injuring scores of others.

In a YouTube video documentary from the rally, Reardon, then 18, says he considers himself a white nationalist and a member of the alt-right, not a neo-Nazi, and adds that he wants “a homeland for white people.”

He says his parents, a “union teacher” mom and “blue-collar worker” dad, don’t agree with his views.

Reardon, who could be seen smirking in his mugshot, was being held on $250,000 bail. He will be arraigned in Struthers municipal court Monday.

Meanwhile, police said they’d were beefing up security at the community center.

The Youngstown Area Jewish Federation thanked cops for their hard work.

“This is a clear example of everything going right. The system worked,” it said in a statement. “We take very seriously the need to be vigilant to ensure the safety of all members of the local Jewish community…”