If they were marching with the old Soviet hammer-and-sickle flag and pictures of Stalin and Che, then you would have an argument to label the activists you mentioned as "extreme left". (Although I'm guessing you meant groups like Black Lives Matter when referring to "radical racial groups" and you will need to explain to me what you consider a radical feminist.) "Left" or "progressive" will suffice. They're not like the anarchists that sometimes show up at marches and do property damage.