I searched the meaning of "thousands" and "hundreds" hundredsThe numbers from 100 to 999. (Lexico Dictionary) thousands The numbers from one thousand to 9,999. so I got to wonder in "hundreds of thousands", what if it's 999(hundreds) of 9,999(thousands) then it becomes approximately 10million.

Understanding the Context

It means that multiple tens of thousands of people are dying. It is an approximation to give an idea of the scale of the number, but it would have to be 20,000 or more to be "tens of thousands".