As a heat wave blasted 17 provinces in China this week, four people died from heatstroke and many suffered in the hot temperature, local news reported on Thursday.

Four elderly people died because of the heat in Zhengzhou, capital of central Henan Province, in the past few days, said the city's 120 emergency center Thursday.

The city's temperature reached a record high this summer of 41.9C (133.02 F) Wednesday, the city's meteorological station said.

The Zhengzhou Emergency Medical Rescue Center said it had received 66 calls for heatstroke cases in the past four days.

That's how it went Thursday in much of north and east China, as a heat wave persisted with temperatures of more than 40 C (129.6 F) in many areas. And according to the Central Meteorological Center, the scorching weather will not end until cold air sweeps from north to south Sunday.

In Nanchang, Jiangxi Province, 300 street sweepers “disappeared” for three days in a row after the local temperature rose to almost 38 C (126F), the Jiangxi Daily reported Wednesday.

Beijing witnessed three hot days in a row from Monday to Wednesday, with the mercury soaring to 37 C (124.2 F) across the city and as high as 40 C (129.6 F) in some areas, the Beijing Meteorological Center said.

The Beijing Meteorological Bureau upgraded its temperature warning to orange alert Wednesday, which meant the temperature had exceeded 37 C (124.2 F)for two days after it issued a yellow alert.

“We sent text messages to people to warn them about the high temperatures and to ask them to be careful of heatstroke,” said Mingying Zhang, a forecaster with the bureau.

The temperature in Hohhot, capital of northern Inner Mongolia Autonomous Region, reached 35 degrees, the highest so far this summer and well above the northern city's average summer temperature of 29 C (109.8 F).

In Jinan, capital of eastern Shandong Province, a few primary schools suspended classes Thursday. Those that stayed open offered cold drinks to their students.

According to the Jinan Education Bureau, if the temperature reaches or exceeds 38 C (126F), schools can suspend classes with the approval of education authorities. On Wednesday, the temperature in Jinan hit 40.8 C (131.04 F).

In a zoo in the northern city of Tianjin, keepers have done their best to keep the animals cool. As the temperature hit 39.7 C (129.06 F) on Wednesday, the zoo, which boasts about 2,000 animals, provided nearly 1 tone of ice, 1 tone of fruit and 300 buckets of mung bean soup to help the animals cool themselves, staff said.

The city has had five days with temperatures of 35 degrees Celsius or above as of Thursday this summer, compared with only four for all of 2008, said Wentao Yu, deputy head of the Tianjin Meteorological Station.

The city will see another sweltering day Friday with temperatures of up to 38 degrees Celsius, Yu said.

The hot weather has led to a peak of electricity consumption in many northern cities. Power use in eastern Anhui Province hit a record high of 284 million kilowatt hours Thursday, up 3% from last year's peak, according to the Anhui Power Company.

It is necessary to legislate that if the heat rises above a certain level, employees should have their working hours reduced or be allowed to take days off, Daidai Lin, a professor at the Beijing Jiaotong University.

Lifu He, chief forecaster of the National Meteorological Center, said such extreme cases of continuous high temperature in north China would persist before cold air arrives on Sunday.