ICA, Peru — The death toll rose to 510 on Thursday in the magnitude-8 earthquake that devastated cities of adobe and brick in Peru's southern desert. Survivors wearing blankets walked like ghosts through the ruins.

Dust-covered dead were pulled out and laid in rows in the streets or beneath bloodstained sheets at damaged hospitals and morgues. Doctors struggled to help more than 1,500 injured, including hundreds who waited on cots in the open air, fearing more aftershocks would send the structures crashing down.

Destruction was centered in Peru's southern desert, at the oasis city of Ica and the nearby port of Pisco, about 125 miles southeast of the capital, Lima.

The United Nations said the death toll was expected to rise beyond the 450 reported by Peru.

"It is quite likely that the numbers will continue to go up since the destruction of the houses in this area is quite total," said U.N. Assistant Secretary-General Margareta Wahlstrom.

Pisco's mayor said at least 200 people were buried in the rubble of a church where they were attending a service. Some 17 others died inside a church in Ica, the Canal N cable news station said. The historic Senor de Luren church was among several heavily damaged in Ica, where at least 57 bodies were taken to the morgue.

Services were packed when the quake struck at 6:40 p.m. Wednesday because Aug. 15 is celebrated by Roman Catholics as the day the Virgin Mary rose up to heaven.

"The dead are scattered by the dozens on the streets," Pisco Mayor Juan Mendoza told Lima radio station CPN, sobbing. "We don't have lights, water, communications. Most houses have fallen. Churches, stores, hotels — everything is destroyed."

The earthquake's magnitude was raised from 7.9 to 8 on Thursday by the U.S. Geological Survey. At least 14 aftershocks of magnitude 5 or greater followed. The tremors caused renewed anxiety, though there were no reports of additional damage or injuries.

President Alan Garcia flew by helicopter to Ica, a city of 120,000 where a quarter of the buildings collapsed, and declared a state of emergency. He said flights were reaching Ica to take in aid and take out the injured. Government doctors called off their national strike for higher pay.

"There has been a good international response even without Peru asking for it, and they've been very generous," Garcia said during a stop in Pisco, where so many buildings fell that streets were covered with small mountains of adobe bricks and broken furniture.