The 28-year-old woman and her one-year-old child made it out of a duplex on 10th near E streets when it went up in flames early Tuesday morning.
A 31-year-old man, and a five-year-old boy and girl were killed.
The coroner's office has identified the man as Ignacio Figueroa-Bautista, the little girl as Geraldine Figueroa-Perez, and the little boy as Jesus Perez-Manzo.
Investigators say the fire started in the living room, but they're still looking into the cause.
The elementary school where the two young victims attended classes has set up an account to help the family.
EECU (Educational Employees Credit Union) in Merced.