Story highlights The 4.3-pound girl is in the NICU of an undisclosed Los Angeles hospital

Authorities are no closer to finding the mother of the girl abandoned Friday

The girl's survival is being called a miracle by authorities who helped rescue her

Los Angeles (CNN) The tiny baby girl pulled alive from a crypt of asphalt and rubble along a popular Compton walking path is being called a miracle by authorities.

Just 4.3 pounds and 15 inches long, the infant is now getting treatment in a neonatal intensive care unit at an undisclosed Los Angeles hospital.

"She was cold to the touch (when rescued)" Friday afternoon, Los Angeles County Sheriff Jim McDonnell said Monday. "The baby would not have survived cold temperatures overnight."

The girl -- estimated to be 4 or 5 days old -- may not have been found if not for the sharp ears of two sisters strolling near the riverbed between 136th Street and Slater Avenue.

"I walk along this path every morning," Evangelina McCrary said. "But it was so cold on Friday that my sister and I decided to walk during the afternoon."

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