ITAJAI, Brazil—Flood victims waded through waist-deep water into mud-filled houses Thursday in a devastated part of southern Brazil where neighbors set up patrols to keep looters away and lined up by the thousands for government food handouts.

As waters from torrential rains receded after causing at least 99 deaths, returning residents heaved soaked furniture and damaged electronic goods into the streets of this coastal city at the mouth of the swollen Itajai-Acu River.

Hunger and thirst were so widespread in the city of 170,000 that police were ordered to let residents take food and water from stores because they were “driven by despair to steal,” said state public safety spokesman Joao Carlos Santos.

Officers instead targeted thieves who paddled rickety canoes and used motor boats to loot abandoned homes.

The official death toll from the rains in Santa Catarina state’s disaster zone rose Thursday to 99 from 97 a day earlier. Mudslides killed most of the victims, and 19 people were officially missing. Authorities said the death toll eventually could climb as high as 150.