SAO PAULO (AP) — While flooding that has devastated Brazil’s Rio Grande do Sul state has yet to subside, another scourge has spread across the region: disinformation on social media that has hampered desperate efforts to get aid to hundreds of thousands in need.

Among fake postings that have stirred outrage: That official agencies aren’t conducting rescues in Brazil’s southernmost state. That bureaucracy is holding up donations of food, water and clothing. One persistent rumor contends that authorities are concealing hundreds of corpses, said Jairo Jorge, mayor of the hard-hit city of Canoas.

Jorge and other officials say hidden actors behind the postings are exploiting the crisis to undermine trust in government.

Ary Vanazzi, mayor of Sao Leopoldo, said many people ignored official warnings and instead heeded social media posts saying government alerts “were just politicians trying to alarm people.”