A student from Marjory Stoneman Douglas High in Florida -- where a mass shooting took place a few years ago -- was met with pure brutality by his own peers ... as seen in this shocking video.

Several clips depicting a recent fight among students at MSDHS are making the rounds online, and in all of them ... you can see one kid getting jumped by multiple other teens who are ganging up on him and pummeling him with blows.

Eventually, you see him get picked up by at least a few students ... who then throw him back on the ground, and he lands awkwardly on his neck and head -- instantly going limp.

Of course, a crowd formed around the chaos ... and most of the students cruelly stood by and watched.

But, some did attempt to check on the boy -- who appeared completely unconscious -- and they rolled him over on his back. You can hear someone ask if he's breathing, but others are more entertained by the fact he was KO'd.

The video is rightly sparking outrage in the community, which already went through utter devastation in 2018 when Nikolas Cruz claimed the lives of 17 people.

There's been speculation this might've taken place on school grounds, in one of the parking lots, but the school principal tells TMZ ... that's not the case.

Michelle Kefford says this took place at a nearby park, and did indeed involve students from Marjory Stoneman Douglas. In a note sent to parents, she adds ... "While this park is not a school or district-operated property, the safety of our students is always our priority, and we are working with law enforcement to help identify those involved."

She continues, "Due to the open investigation, I am not able to provide additional details, but I want to assure you this situation is being taken seriously. Please do remind your students to say something if they see something. As always, thank you for your support."