Death toll from a devastating flood in south-western Nigeria has reached at least 20 people, world media said on Sunday referring to the country\'s emergency agency. \"The death of 20 people has been officially confirmed. The flood has destroyed a dumb, the situation is very serious,\" agency\'s chairman Yushau Shuaib said. Torrential rain which began on Friday triggered the flood. Thousands of people have been evacuated from the area, local media said.