The attack early Sunday morning left 54-year-old Pedro Reyes with severe facial fractures, missing teeth and lacerations. He is expected to undergo surgery Monday.
Reyes was among a group of street vendors setting up their stands near Exposition Park early Sunday when two cars pulled up, and a group of people began attacking them.
Two other vendors suffered minor injuries.
Video shows attack on street vendor near Expo Park
Reyes' stepson says the man complied with his attackers' demands.
The video shows at least three members of the group assaulting the vendor and throwing him to the ground in the middle of the street, where he appears to hit the ground face-first.
They then stand over him and search through his pockets as he remains motionless on the ground.
Police are trying to track down the attackers.
A GoFundMe account has been established to help Reyes and his family.