Washington told People magazine he regretted his action and "the unfortunate use of words" during the dust-up.
The clash reportedly involved the use of some homophobic slurs and occurred 10 days before cast member T.R. Knight told People that he was gay.
People said the turmoil has stirred up plenty of rumors, including script rewrites and the possibility that Washington could be sacked and replaced with "ER" alumnus Eriq La Salle -- a scenario that show creator Shonda Rhimes said was not true.
Celebrity Families of 2014 [PHOTOS]