The blaze that burned into yesterday morning destroyed the ornate, gilded altar and about two dozen paintings at the Temple of San Sebastian.
Architect Americo Carrillo, who led a USD 2 million restoration of the church between 2008 and 2013, characterised the loss as irreparable. He said the baroque church was "a jewel of Peru's colonial era."
Firefighters said they lacked sufficient water to fight the fire, so neighbours pitched in by bringing water from home cisterns. Priests rang the church bells to summon help as the fire advanced.
Among the treasures lost were colonial era oil paintings by well-known indigenous artist Diego Quispe Tito depicting the life of St Sebastian, Carrillo said.
The temple is well-known among international visitors to Peru's Andean region, located about a 10-minute drive from the city centre of Cuzco, which was the capital of the Incan empire.
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