A mass fish die-off in a reservoir in southern Vietnam’s Dong Nai province has shone a new light on soaring temperatures in Southeast Asia.

Fishermen have been working to wade through and collect the hundreds of thousands of dead fish that have blanketed the 300-hectare Song May reservoir amid a ferocious heatwave.

Intense drought swept through Vietnam’s south in April as temperatures soared to nearly 40 degrees Celsius (104 degrees Fahrenheit), leaving farmers struggling to keep their crops alive.

Community members and local media are blaming the drought, heatwave and problems with the reservoir’s management as contributing factors.