From ABC News:
An internal U.S. Capitol Police bulletin distributed Tuesday contains information about a possible militia plot to storm the Capitol on or around March 4, sources told ABC News.
The information in the bulletin is sourced to an FBI intelligence report from late February that describes the an alleged plot by the “Three Percenters militia group to use diversionary tactics such as detonating a bomb” to draw law enforcement away from the Capitol prior to an attempt by the group to take over the U.S. Capitol, according to a law enforcement source.
The credibility of the information in the bulletin remains unclear.