Eleven drainage workers were confirmed dead on Friday, one day after flash floods hit the southern Chinese city of Shenzhen.

The victims were among 16 people cleaning drainage systems in the Luohu and Futian districts of the city when the downpour hit, triggering flash floods. Nine workers were confirmed dead on Thursday night. Five were rescued and two missing workers were confirmed dead on Friday after a day of searching, putting the death toll at 11.

The incident came despite the city government having issued a weather alert to construction companies, asking them to handle the cofferdams carefully.