SURFSIDE, Fla.—Fire and smoke coming from deep inside the concrete and metal remains of a collapsed 12-story condominium tower near Miami hampered rescue efforts Saturday, as emergency workers raced to recover any survivors beneath the mountain of rubble. Rescuers used infrared technology, water, and foam to battle the blaze, the source of which was unclear, and Miami-Dade Mayor Daniella Levine Cava said the smoke has been the biggest challenge. In a news conference, she described the blaze as “very deep” and said rescuers faced “incredible difficulties” because of the flames. A fire hose blasted one of the lower floors on the north side of the tower as white smoke or steam streamed out, and a bitter, sulfur-like smell hung in the air. “The stench is very thick,” Florida Gov. Ron DeSantis said. A crane removed pieces of debris from the more than 30-foot pile in the city of Surfside, and …