Thousands of fish have died as a lagoon in northern Mexico partly dried up amid a crippling drought plaguing the country.

The Bustillos lagoon was below 50 percent of its normal water level, local authorities said Wednesday, meaning pollutants were more concentrated and hazardous to the species that inhabit it.

Dead fish started piling up in the lake bed's cracked mud a week ago, and a foul smell hung over the area Wednesday as workers cleaned up the decomposing remains amid fears they could spread disease.

Mexico as a whole has been battling high temperatures with a dozen cities, including the capital, breaking heat records.

Health authorities say 125 people have died in the current hot season, which started mid-March.