Fla. man allegedly posted on social media that he planned racially motivated mass violence: DOJ

A 26-year-old Florida man with ties to the Aryan white supremacist movement has been charged by federal prosecutors after he allegedly warned online "that he was planning to conduct a racially or ... ethnically motivated mass casualty event," according to court documents unsealed on Thursday.

Alexander Lightner, of Venice, Florida, is charged with interstate communication of threats. He is accused of posting "several concerning" things on social media on Dec. 29, the court documents state.

"2024 there shall be saints u fuq," he allegedly wrote in one post. "I'll delete this, but I say to you there is no surrender only death. Only purpose. It's so over. It's so begun."

The reference to "saints" is "an individual who commits an act of violence in furtherance of white supremacist and accelerationist goals," according to the Department of Justice.

On social media, Lightner allegedly also made reference to getting a "highscore" which, according to the DOJ, is a reference to the death toll amassed by an attacker who commits an act of mass violence.

On Friday, law enforcement raided Lightner's home and allegedly found multiple firearms in his room, .308 ammunition and a silencer.

"Federal agents also found propaganda regarding white supremacist and accelerationist ideology in LIGHTNER's bedroom," the court documents state.

He was arrested on Monday, according to court records.

A lawyer for him did not respond to ABC News' request for comment. He has not yet entered a plea and remains in custody.

Federal law enforcement authorities have repeatedly warned that domestic extremists pose a serious risk to the country.

Homeland Security Secretary Alejandro Mayorkas testified before Congress last year that they are "the most significant and persistent terrorism-related threat to the homeland."