It's a miracle Demaryius Thomas wasn't killed in his car crash Saturday morning -- with a key witness telling TMZ Sports he watched DT's car flip 3 times ... and was SHOCKED when he saw the NFL star get out of the vehicle mostly unharmed.
We spoke with Michael Tafoya who happened to be driving in the Denver area around 12:20 AM when he saw the vehicle lose control, hit a curb and launch 20 feet into the air. The car then rolled 3 times before finally landing in a grassy median.