MIAMI -

Miami-Dade rescuers will turn their efforts from search and rescue to recovery after a worker fell 140 feet into a silo containing tightly packed cement dust after a roof collapse.

Miami-Dade Fire Rescue responded to a call Friday morning from the Titan America cement plant in Medley. A head count was performed after the collapse, and one worker, 58-year-old Pierre Mezidor, was missing.

The Miami Herald reports that rescuers brought two 200-foot cranes and a bucket lift to the factory Friday afternoon.

Rescue efforts continued through the day. After exhausting all search and rescue efforts, Miami-Dade police say the rescue switched to a recovery and the investigation was turned over to the department's homicide bureau.

Officials are trying to determine what caused the roof collapse.