The entire state of Florida is classified as a karst landscape, which is formed when water dissolves carbonate bedrock, often limestone. A collapse can be triggered by a change in groundwater levels or heavy rainfalls. The collapses can leave even larger holes underground. (Via U.S. Geological Survey)
The holes left behind can be filled with a combination of sand and cement. Another technique called compaction grouting can also be used. Soil is injected into the earth and displaces the ground around it, making it more compact. (Via YouTube / Steve Marsh, Trial Exhibits, Inc.)
Police will continue to monitor the Spring Hills sinkhole through Sunday, when the cleanup process can begin.