It may be week one of the preseason, but Rams and Cowboys fans are in midseason form ... 'cause loyal supporters of the organizations went toe-to-toe in a bloody brawl outside SoFi Stadium.
The fight went down right outside the SoFi gates in Los Angeles ... where video shows a fan wearing an Aaron Donald jersey getting thrown to the ground by a guy rockin' Troy Aikman threads -- before delivering some big blows to the head of the guy on the ground who appears to be out cold.
The camera then pans over to a group of women also going at it ... with one being dragged by the hair. One of the women turns her attention to a guy in a Puka Nacua jersey, and takes a swing at him ... all while you can hear a little girl screaming in the background.
Another video shows what seems to be the end of the incident -- with the two women finally getting separated -- and the person behind the camera attempting to ease tensions and prevent the incident from getting even worse.
We've reached out to cops to see if there have been any arrests ... but so far no word back.
On the field, while it wasn't the most thrilling game, the Rams took home a 13-12 victory against the Cowboys -- thanks to a game-winning drive from Stetson Bennett -- who returned after taking last season off due to health reasons.