BATON ROUGE, La. — Authorities went door to door and car to car to check for bodies Tuesday, and homeowners began the heartbreaking task of gathering up soaked family photos and mucking out houses dank with bayou mud, as the floodwaters started to recede across parts of southern Louisiana. Even as the water fell in some areas, it was rising in other places downstream, where people furiously filled sandbags and fled to shelters. Officials painted a stark picture of the crisis so far: at least 40,000 homes damaged and 11 people killed in some of the worst flooding in Louisiana history, touched off by as much as 2 feet of rain in 48 hours.