The incident occurred when a bus collided with a truck on a highway north of the capital, Lima. Traffic accidents are common in Peru, killing more than 2,600 people in 2016.
At least 48 people were killed when a bus tumbled down a cliff onto a rocky beach Tuesday along a narrow stretch of highway known as the 'Devil's Curve', Peruvian police and fire officials said.
The bus carrying 57 people was headed to Peru's capital when it was struck by a tractor-trailer shortly before noon and plunged down the slope, said Claudia Espinoza with Peru's voluntary firefighter brigade.
The blue bus came to rest upside down on a strip of shore next to the Pacific, the lifeless bodies of passengers strewn among the rocks.
"It's very sad for us as a country to suffer an accident of this magnitude," Peruvian President Pedro Pablo Kuczynski said in a statement.
Rescuers had to struggle to rescue survivors and recover the dead from the hard-to-reach area in Pasamayo, about 70 kilometres (43 miles) north of Lima.
No road leads directly to the beach, complicating rescue efforts, Espinoza said. Police and firefighters used helicopters to transport six survivors with serious injuries to nearby hospitals. Colonel Dino Escudero said 48 people were confirmed dead and at least three were missing.
Transportation Minister Bruno Giuffra said initial reports indicated both vehicles involved were travelling at a high rate of speed at the time of the crash.
As rescue operations continued late into the night, authorities announced a suspect had been detained for allegedly robbing belongings of victims.
Traffic accidents are common
Traffic accidents are common along Peru's roadways, with more than 2,600 people killed in 2016. More than three dozen died when three buses and a truck collided in 2015 on the main coastal highway. Twenty people were killed in November when a bus plunged off a bridge into a river in the southern Andes.
The nation's deadliest traffic crash on record happened in 2013 when a makeshift bus carrying 51 Quechua Indians back from a party in southeastern Peru fell off a cliff into a river, killing everyone on board.
Espinoza said the passengers in Tuesday's crash included many returning to Lima after celebrating the New Year's holiday with family outside the city.
The highway is known as the 'Devil's Curve' because it is narrow, frequently shrouded in mist and curves along a cliff that has seen numerous accidents. Police said the bus fell an estimated 80 metres (260 ft).