The earthquake, centered in Peru's southern desert, collapsed buildings, toppled power lines -- cutting off communication from the capital Lima to the destruction zone, and blocked highways with boulders.
International aid officials and Peruvian leaders said they worried the death toll would continue to mount.
"It is quite likely that the numbers will continue to go up since the destruction of the houses in this area is quite total," U.N. Assistant Secretary-General Margareta Wahlstrom said, according to the Associated Press.
Although communication to the affected region remained spotty, reports of towns and cities devastated by the temblor continued to trickle in Thursday.
In Ica, a city of about 120,000, four buildings fell and at least 57 bodies were brought to the morgue, the AP reported.
Nearby in the port town of Pisco, about 200 people who were attending church services were trapped under rubble, according to Mayor Juan Mendoza.
At a damaged hospital in the small town of Chincha, an AP television cameraman counted 30 bodies lying under sheets, and at least 200 injured people waited for treatment outside, for fear aftershocks would cause the hospital's cracked walls to crumble.
"Our services are saturated and half of the hospital has collapsed," said Dr. Huber Malma.
The government rushed police, soldiers, doctors and aid to the affected areas, but it was unclear when they would be able to reach their destinations.
The Peruvian Red Cross arrived in Ica and Pisco 7 1/2 hours after the initial earthquake, about three times as long as it would normally take because of road damage, the AP quoted Red Cross official Giorgio Ferrario as saying.
In the poor Canete neighborhood Imperial, people were forced to sleep outside of their damaged homes, lighting fires to keep warm, Reuters reported.
"The situation is critical in Imperial," said Mayor Richard Yactayo. "About 80 percent of the adobe houses have fallen and houses of stronger material also have collapsed."
Although the quake was one of the strongest to strike the region, Peru is no stranger to natural disasters.
In 1970, about 50,000 Peruvians died in one of the world's worst earthquakes, which triggered ice and mudslides that buried the town of Yungay, according to Reuters.
