China's weather forecast authorities said Tuesday that rains are expected to fall on parts of east China starting Thursday, offering some respite to a wide-ranging heat wave that had wreaked havoc across the country over the past few days.

A street cleaner is soaked in perspiration on Tuesday in Zhengzhou, capital of Henan province, where the mercury hit 38 C.

From Beijing in the north to Guangzhou in the south, a number of the elderly and children were hospitalized for heat-related illnesses. Some zoo animals died or struggled to survive by laying on ice.

Also, a passenger bus caught fire in downtown Beijing and swarms of locusts blanketed a couple of dry prairies and grasslands in the north.

The National Meteorological Center (NMC) raised the heat alert to orange on Tuesday, one step before the highest level, and said at least 16 provinces, autonomous regions and municipalities were enduring the extreme heat.

In Beijing, the temperature shot up to 40.6 degrees Celsius, breaking the city's early July heat record in more than 50 years. Further, the extreme high temperatures would continue in north, east and west China for the next 24 hours before rains begin to fall, the authorities said.

"Every day we have about 300 patients, 100 more than the average," Qin Jian, head of the emergency unit of Xuanwu Hospital in Beijing, said. "The wards and emergency rooms have been full right from the morning."

Qin said most of the patients were the elderly who suffered from cardiovascular diseases due to the heat.

On the 3rd Ring Road of Beijing, a passenger bus was engulfed by a blaze caused by a leak of the gas pipe due to an overheated generator. All passengers were evacuated but the bus was completely destroyed.

Huge swarms of locusts are ravaging grasslands and farmlands from Inner Mongolia Autonomous Region to Xinjiang Uygur Autonomous Region, prompting authorities to use aerial spraying of pesticides to kill the insects.

In Inner Mongolia alone, locusts have infested 3.9 million hectares, or 4.5 percent of the region's total area of grasslands.

More than 6,000 people and five planes were enlisted for locust control, completing nearly 130,000 hectares of pesticide spraying, authorities said.

In Hebei Province neighboring Beijing, local weather forecast authorities issued red, or the highest-level, heat alert Tuesday morning, after maintaining an orange-level alert for ten days.

Sales of refrigerators and air-conditioners surged in Hebei provincial capital Shijiazhuang. Many working parents sent their children to air-conditioned bookstores to escape the heat, and cab drivers said business was brisk during these hot days.

In northern port cities of Dalian and Qinhuangdao, large crowds swam in coastal waters to escape the heat.

Weather forecasters said the sweltering heat in northern China would be largely diminished by an expected rainfall on Thursday.

In central and southern China, however, no immediate let up of the heat wave is foreseen.

In Hunan's provincial capital Changsha, a red deer died at a zoo due to a lack of water.

"It has been around 40 degrees Celsius for days, creating so much demand for water that units at the water system's far edges face shortages," Changsha Ecological Zoo official Zheng Chuang told the media.

Pictures of giant pandas crouching on huge ice blocks splashed across newspapers.

While animals were taken care of, governments and firms across the country offered breaks or bonuses for those who labored outdoors.

However, steel workers in Shijiazhuang continued with their work in extremely hot and humid workshops, having rubbed on cooling ointment and sipping cold drinks. Freezers in a steel factory's air-conditioned break room were filled with bottled water, ice cubes and ice cream.

As stipulated by the municipal construction bureau, construction workers in Shijiazhuang have stopped working from noon to 2 p.m. to prevent heat fatigue.

But a Xinhua reporter found the temperature at a residential building construction site reached 44 degrees Celsius at 3:30. Some workers said they still could not bear the heat even after 2 p.m.

Despite the extreme heat, Wang Hongze, a 48-year-old construction worker in the southwest Chinese city of Nanning, said he would not ask for a day's leave. "I can't afford to lose 120 yuan (17.7 US dollars) a day. I'm working hard to pay my son's college fees."

In Beijing, the government is mulling whether to raise the minimum allowance of those working in the heat from 60 to 120 yuan per month.