Some 224 people are now believed to have died during a heatwave in Pakistan's southern Sindh province.
Health officials say most of the deaths have been in the largest city, Karachi, which has experienced temperatures as high as 45C (113F) in recent days.
The city has seen power cuts caused by an increased demand for electricity because of the extreme weather.
Many of the victims are elderly people who have been suffering from fever, dehydration and gastric problems.
Hundreds of patients suffering from the effects of the heatwave are being treated at government hospitals, provincial health secretary Saeed Mangnejo said.
Local media report that more than 150 bodies have been taken since Saturday to the Edhi morgue in Sohrab Goth, which usually receives about 20 bodies a day.
The demand for electricity for air conditioning has coincided with increased power needs over Ramadan, when Muslims fast during daylight hours.
Hot weather is not unusual during summer months in Pakistan, but prolonged power outages seem to have made matters worse, the BBC's Shahzeb Jillani reports.
Sporadic angry protests have taken place in parts of the city, with some people blaming the government and the city's main power utility, K-Electric, for failing to avoid deaths, our correspondent says.
How the body copes with extreme heat
The body's normal core temperature is 37-38C.
If it heats up to 39-40C, the brain tells the muscles to slow down and fatigue sets in. At 40-41C, heat exhaustion is likely - and above 41C, the body starts to shut down.
Chemical processes start to be affected, the cells inside the body deteriorate and there is a risk of multiple organ failure.
The body cannot even sweat at this point because blood flow to the skin stops, making it feel cold and clammy.
Heatstroke - which can occur at any temperature over 40C - requires professional medical help and, if not treated immediately, chances of survival can be slim.
There is a number of things people can do to help themselves. These include:
- drinking fluids
- wearing damp clothes which will help lower the body's temperature
- sticking one's hands in cold water
- placing fans next to windows as this will draw air from outside, which should be cooler
- wearing looser clothes
- having a lukewarm shower rather than a cold one
- fanning the face rather than other parts of the body
Karachi resident Iqbal told the BBC no-one in his family could go outside to work because of the temperature and that everyone in their area preferred to stay at home.
"In our area, there is no electricity [since the] morning. We have complained several times, but there is no response from K-Electric," he said.
According to Pakistan's metrological office, very hot and humid weather is likely to continue on Monday, but cooler weather is forecast from Tuesday.
The all-time record temperature in Karachi is 47C (117F), recorded in 1979.
Nearly 1,700 people died in a heatwave in neighbouring India last month.