FBI agents arrested Massachusetts Air National Guardsman Jack 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. Police vehicles were seen at a Massachusetts location believed to be connected with the guardsman. The guardsman's security clearance and access to classified government systems have been revoked, according to an internal government document reviewed by Fox News. The guardsman worked on military intelligence systems on a full-time basis, Fox News is told. The National Guard said in a statement it is aware Thursday of the…