Protesters angry at frequent power cuts have again taken to the streets of Pakistan's biggest city, Karachi.
Anger has erupted in poorer, crowded areas
The regular electricity outages come amid a heat wave, and violent protests have become a daily occurrence, with a number of attacks on power workers.
Friday's protests were in poorer areas of the city which have been hard hit. In recent days tyres have been burned and commuters pelted with stones.
Pakistan's power grid is run down and cannot keep up with demand.
"How can they expect us to go without power in this weather? Our children can't sleep at night," businessman Ahmed Anwar told Reuters news agency.
The BBC's Aamer Ahmed Khan in Karachi says the power cuts, at a time when temperatures have been rising as high as 37C, are the worst to hit the city in recent years.
The outages can last up to half a day, he says, with crowded, lower-middle class areas suffering in particular.
The provincial government have ordered traders in the city to close shops early to help conserve power.
The traders are currently negotiating for an extension to their hours if they use their own generators.
Many of Karachi's key facilities, including hospitals, and businesses rely on generators to keep them supplied with electricity because of the frequent power cuts.
The Karachi Electric Supply Corporation is the sole electricity distributor in the city of 15 million people.
It was privatised in the past year, and many people say they feel not only angry but helpless because no-one answers their complaints.
The company says part of the problem is illegal connections and disgruntled workers sabotaging the lines.
It promises to increase capacity later this year.
In some places its workers have had to repair power lines under police protection because of angry crowds.
Pakistan's power authorities in the capital, Islamabad, say national demand for electricity outstrips what Pakistan's grid can supply by about 700 megawatts a day.
About 500 megawatts are lost in the distribution process because of the dilapidated network, they say.