When water leaks and flooding occur you need to find a professional and get the process of cleaning and drying going within 24-48 hours.  When quick detection of water or moisture doesn't happen the odds increase that mold will be growing.  There are times when water and moisture exposure happen slowly and you don't even realize it's happening.  Unfortunately, just because mold isn't visible, it doesn't mean the mold isn't there.  It might be behind walls, under flooring, in crawl spaces or attics, and hidden from easy observation.  That's why contacting a professional is needed for mold assessment and cleaning.  You can find a professional by searching a Flood Damage Directory with this link https://www.ijcsa.org/Flood-Damage-Restoration-Services