The US Geological Survey reported the quake struck on Saturday at 9.24pm, with its epicentre located 2km west-southwest of the city of Sicaya in Huancayo province.
It was 10km deep.
Peru's National Civil Defence Institute said in a statement the total number of missing is still unknown.
Several buildings collapsed or suffered structural damage, including the historical Santiago de Leon church and former convent in Chongos Bajo, which was built in 1565 and designated as national heritage site for being a 16th century "architectural gem".
Luis Vásquez, head of the local civil defence office, told journalists that the use of rustic adobe materials in construction in the Andean area "has contributed to the greater impact and damage".
Earthquakes are frequent in Peru, which is located in the so-called Pacific Ring of Fire.
Images broadcast by local media captured the anguish of victims' relatives in one of the hardest-hit areas, the agricultural region of Chongos Bajo, where residents huddled under blankets outside severely damaged homes.
Animals were also seen under the rubble.
"My home has been destroyed," Hermenegilda Guamalato told a local radio station as she sought a place to stay with her three children in the neighbouring province of Huayucachi.
In 2007, a magnitude 7.9 earthquake struck the province of Pisco in the Ica region, killing nearly 600 people.
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