FBI arrests Massachusetts Air National Guardsman Jack Teixeira in probe of classified document leaks
Jack Teixeira, 21, was arrested in Massachusetts on Thursday

FBI agents arrested Massachusetts Air National Guardsman Jack Douglas Teixeira at a home in North Dighton, Massachusetts, on Thursday in relation to a trove of classified documents that have been leaked online in recent months.

Attorney General Merrick Garland said that Teixeira, 21, is being investigated for the "alleged unauthorized removal, retention, and transmission of classified national defense information."

A large police presence could be seen at the home in North Dighton, which is about 35 miles south of Boston.

Teixeira, who worked on military intelligence systems on a full-time basis, had his security clearance and access to classified government systems revoked, according an internal government document reviewed by Fox News.

The National Guard said in a statement it is aware of the "alleged role a Massachusetts Air National Guardsman may have played in the recent leak of highly-classified documents" from the Pentagon.

"The National Guard takes this issue very seriously and will support investigators," the National Guard said in a statement. "National security is our foremost priority and any attempt to undermine it compromises our values and degrades trust among our members, the public, allies and partners.

Pentagon Press Secretary Brig. Gen. Pat Ryder called the leaks a "a deliberate criminal act," saying that distribution lists for classified information are being reviewed.

"We entrust our members with a lot of responsibility at a very early age," Ryder said at a press conference on Thursday.

"You've received training and you will receive an understanding of the rules and requirements that come along with those responsibilities, and you're expected to abide by those rules, regulations and responsibility. It's called military discipline. And in certain cases, especially when it comes to sensitive information, it also is about the law."

The New York Times originally identified Teixeira as the suspected leaker on Wednesday evening, reporting that he was the leader of a Discord group consisting of roughly 20 to 30 young men that went by the name Thug Shaker Central.

Teixeira allegedly starting sharing classified documents with the private group in recent months, but the leaks gained wider attention after another member shared them in a public forum, according to the report.

Deputy Secretary of Defense Kathleen Hicks sent a memo to Pentagon officials on Tuesday, warning employees against leaking classified information or downloading classified documents from unclassified sources.

"Do not access or download documents with classified markings from unclassified websites   either from home or work   as the data ma y be classified, it may be associated with hostile foreign elements, or it may contain malicious code or embedded capability that could introduce cyber threats into our information system," Hicks wrote in the memo, which was obtained by Fox News.

President Biden said earlier Thursday that the U.S. was "getting close" to finding the person responsible for leaking Pentagon documents that the Department of Defense has described as containing "sensitive and highly-classified material."  

"I can't right now [give an update]. There is a full-blown investigation going on with the intelligence community and Justice Department and they are getting close," Biden told reporters during his trip to Ireland. "I don't have an answer for you."  

The president also said, "I'm concerned that it happened, but there is nothing contemporaneous that I'm aware of that is of great consequence."  

The Washington Post first reported last night that the person behind the leaks worked on a military base and shared the classified information on the chat app Discord.

The top-secret intel that has been shared online included movements of high-ranking political leaders, updates on military forces, detailed charts of battlefield conditions in Ukraine and satellite images of the aftermath of Russian missile strikes on Ukrainian facilities. Other documents, according to the report, included the potential trajectory of North Korean ballistic nuclear missiles that could reach the U.S. and pictures and information on the surveillance technology attached to the Chinese spy balloon that the Biden administration allowed to float across the U.S. in February.