Al Jazeera's Gabriel Elizondo in Pisco, close to the epicentre of the quake, said the town had been reduced to a pile of rubble.
"Eighty per cent of the buildings in the town have been destroyed. I saw bodies being brought out from inside a church and laid in the town square."
Juan Mendoza, the mayor of Pisco, said: "We have hundreds of dead lying in the streets, and injured people in the hospital. It is totally indescribable.
"We don't have water, no communications, the houses are collapsed, the churches are destroyed."
Hospitals were destroyed and many of the wounded were being brought to Lima, the capital.
|Survivors were being carried |
from the rubble [EPA]
The earthquake occurred at 6:40pm (2340 GMT) on Wednesday and was felt for a number of minutes.
The US Geological Survey upgraded the quake's magnitude to 8.0 from an earlier 7.9 measurement, and powerful aftershocks rattled the country on Thursday morning.
Buildings collapsed, major motorways to the coast were destroyed and power lines knocked out.
Hundreds of prisoners escaped from Tambo de Mora prison, in the city of Chincha.
Tens of thousands of panicked Lima residents spent the night on the streets fearing more tremors.
As rescuers scrambled through the debris, dazed residents guarded bodies in the street, not sure where to take them.
Jose Flores, a boy of about 12-years old, stood near the body of his dead mother on the pavement outside their destroyed home in Chincha.
"We don't know what to do. I don't know where to hold a wake for her... The wall just came down and crushed her when I was outside."
The health ministry made an emergency appeal for blood donations.
Carlos Vallejos, the health minister, travelled overnight to the town of Ica to survey the damage.
The government also sent a convoy of lorries to the region carrying medical supplies, doctors and nurses but damaged roads were hampering relief efforts.
The UN said it was ready to help and the International Federation of the Red Cross said two aeroplanes carrying tents, plastic covers, blankets and water canisters would leave Panama City for Lima on Thursday.
It was the biggest earthquake to hit the South American nation in decades.
The USGS said the quake was centred about 145km southeast of Lima at a depth of around 40km and was closely followed by nine aftershocks.