The mother of one of the surviving women told CNN affiliate KTVU that her daughter, Mary Guardiano, was upset but physically OK.
"She's very sad. She is crying," said Rosita Guardiano.
In a written statement, the limousine company said it was "deeply saddened" by the deaths.
"LimoStop Inc. will do everything possible to investigate and assist authorities in determining the cause of this fire in order to help bring forth answers and provide closure to the victims and their families," it said.
Medical examiners may need up to two days to positively identify the remains, San Mateo County Deputy Coroner Roger Fielding said.