8/31 5:28 AM PT -- New video from the concert obtained by TMZ shows Isaac Freeman, aka Fatman Scoop, walking around the stage without a shirt on before he collapses.

7:45 PM PT -- Hamden Mayor Lauren Garrett said via social media that Fatman Scoop was being transported by ambulance to the hospital. "Please keep him in your thoughts and prayers."

Scary scene at the Fatman Scoop concert ... after he passed out onstage and got CPR ... and TMZ has it all on video.

The legendary hip hop hype man was performing Friday at Town Center Park in Hamden, CT when he appeared to suffer a medical emergency.

Folks who were there say Fatman Scoop collapsed and passed out ... with people rushing over to administer CPR. Authorities tell us they were dispatched for a medical emergency at 8:33 PM.

Video shows medical personnel performing chest compressions on someone behind the DJ booth ... folks in the crowd say it's Fatman Scoop.

The music suddenly stops and a hush falls over the crowd ... and you hear murmurs about Fatman Scoop getting CPR.

The person who took this video says they saw Fatman Scoop fall over ... and he was ultimately taken out on a stretcher.

Unclear what may have caused this whole thing ... but hopefully Fatman pulls through.

Fatman Scoop's worked with a ton of big names in hip hop over the years ... collabing with the likes of Missy Elliott, Mariah Carey and Jermaine Dupri ... just to name a few.

We reached out to Fatman Scoop's camp ... so far no word back.