Police in the US state of Ohio have arrested a man they believe threatened to carry out a shooting at a Jewish community centre.
James Reardon, 20, posted a video online of a man firing a gun with a caption identifying the centre in Youngstown, north of Pittsburgh.
A search of his home revealed several weapons, body armour and a gas mask, police said.
A shooting at a synagogue in Pittsburgh last year left 11 people dead.
James Reardon was arrested in New Middletown, near Youngstown, on Saturday and charged with menacing and harassment. He is due to appear in court on Monday.
Investigators said the alarm was raised when a post appeared on Instagram showing a man firing a gun with the caption: “Police identified the Youngstown Jewish Family Community shooter as white nationalist Seamus O’Reardon.”
New Middletown Police Chief Vince D’Egidio said they believed Seamus O’Reardon was a pseudonym for James Reardon.
“He was implying that he was going to be identified as the shooter of the Jewish centre. That kicked off a very intensive investigation, a very rapidly evolving investigation,” he said, quoted by WKBN-TV.
Security at local Jewish facilities was increased and the FBI was contacted, Chief D’Egidio added.
As well as a cache of weapons, the search of the suspect’s home also uncovered white nationalist material, police said.
After the arrest, the Youngstown Area Jewish Federation issued a statement thanking law enforcement agencies for their swift action.
The attack on the Tree of Life Synagogue, in Pittsburgh, last October was believed to be the worst anti-Semitic attack in US history.
Suspected gunman Robert Bowers has been charged with the killings and if found guilty faces life in prison without parole.
Mr Reardon’s alleged plot was one of three apparently prevented by local authorities this weekend, US media report.
Two more men – one in Florida and another in Connecticut – were arrested after sending messages related to potential mass shootings, CNN report.