NBC News Congressional reporter Frank Thorp confirmed the person who yelled the obscenity at the president was a congressional intern.
Per our intern, who was standing there, the woman who yelled "Mr. President, F--k you!!" was a congressional intern.— Frank Thorp V (@frankthorp) June 19, 2018
FOX News' Chad Pergram also reported the same:
Congressional aide or intern yells “Mr President, f*%k you!” from across the Capitol Rotunda as he walks to the Speaker’s office before mtg with House GOPers on immigration. Gets attention of USCP/Secret Service pic.twitter.com/5Uarw4FTsw— Chad Pergram (@ChadPergram) June 19, 2018