As entire communities lie in ruins after swollen rivers swept through towns and villages in Western Europe, experts said the ferocity of the rainfall and failure to heed warnings about its arrival were likely responsible for the high number of deaths.

a person walking down the street© Provided by NBC News

At least 120 people have been killed in the flash flooding and thousands more are missing in Germany and Belgium. Cellphone networks have collapsed in some regions, leaving people unable to track down their loved ones. Luxembourg and the Netherlands were also hit with heavy downpours.