Really, just an amazing run. Breaking a 4:00 mile is still fairly rare. Averaging 3:57 over 2 miles is ludicrous. Dude's a beast. And he pulled up at the end. Could have been slightly faster.
3200 meters is 10498.7 ft; 2 miles is 10560 ft. A number of sources have said it was 2 miles - it could be bad reporting.
If it was 3200 meters, it would take another 7 seconds or so to make 2 miles.