CNN  — 

Sounds offer hope, officials said Friday amid a frantic, fast-paced mission to find survivors trapped beneath the rubble of a partially collapsed condominium tower in Surfside, Florida.

Though it’s unclear how many people were in the portion of the 12-story building that fell, scores of victims remain unaccounted for. The death toll has risen to four.

Rescuers above and below the rubble are using light and heavy machinery, along with an array of technology, in their search, said Raide Jadallah, assistant chief of operations for the Miami-Dade Fire Rescue Department