LUJAN, Argentina—More than 11,000 people had been evacuated by Tuesday from parts of Argentina’s largest province after heavy weekend rains caused rivers to rise precipitously, a top official said.

After a visit to the worst flood-hit areas, National Security Secretary Sergio Berni told reporters late Tuesday that the 11,000 evacuees hail from 39 municipalities in Buenos Aires province. Local television reports showed emergency workers traversing streets in boats in some areas.

...