People wearing sunglasses rush along the street, buses have their air conditioners cranked up, and everybody does their best to minimize the time spent outside.

That's how it went Thursday in much of north and east China, as a heat wave persisted with temperatures of more than 40 degrees Celsius 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.

A heat wave hit Beijing on June 24. Heat wave persiss with temperatures of more than 40 degrees Celsius in many areas in China on these days.

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

The city's temperature reached a record high this summer of 41.9 degrees Wednesday, the city's meteorological station said.

Su Shaobo, a worker at a construction site in Hohhot, capital of northern Inner Mongolia Autonomous Region, said his afternoon starting time had been delayed one hour to 4 p.m. to avoid the midday heat Thursday.

The temperature in Hohhot reached 35 degrees, the highest so far this summer and well above the northern city's average summer temperature of 29 degrees Celsius.

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 degrees Celsius, schools can suspend classes with the approval of education authorities. On Wednesday, the temperature in Jinan hit 40.8 degrees Celsius.

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 degrees Celsius Wednesday, the zoo, which boasts about 2,000 animals, provided nearly 1 tonne of ice, 1 tonne of fruit and 300buckets 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 Yu Wentao, 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.

In the northwestern ancient city of Xi'an, an air-raid shelter opened for free on Thursday for residents seeking to cool off. The temperature in the shelter was about 23 degrees Celsius, compared with 38 degrees outside.

The facility could accommodate some 2,000 people daily during its service time from 1:30 p.m. to 10 p.m., the Xi'an city government 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 percent from last year's peak, according to the Anhui Power Company.