TMZ Sports has obtained insane footage of ex-NFL quarterback Marcus Vick -- Michael Vick's brother -- literally running from cops during an incident back in April ... before being captured at gunpoint.
It all started at a gym in Newport News, Virginia -- when cops were questioning the 32-year-old about a warrant out for his arrest stemming from a civil case.
Vick spoke with cops for nearly 10 minutes before suddenly deciding to make a run for it -- shoving 2 cops out of the way, breaking tackles -- and SPRINTING down the street.