According to Brazilian MMA magazine Tatame, Ribeiro's coach Luiz Alvez said the crash happened around 1 a.m. and that Ribeiro was not wearing a helmet.
Ribeiro's manager Ed Soares added on a report on the official WEC website that Ribeiro was riding passenger and is now fighting for his life.
"My assistant said that the doctor said for sure that he has lost sight in one of his eyes," Soares said, according to WEC.tv. "He's still in a coma. After surgery the doctor said there is a 50-50 shot that he will come out of it."
Ribeiro (10-2) made his American television debut earlier this month at the Versus-televised WEC 37: Torres vs. Tapia event, losing to Brian Bowles via guillotine choke in the third round. In June, Ribeiro won a split decision over former WEC bantamweight champion Chase Beebe.