Muddy water spilled onto streets and into homes on Thursday in a new round of unusually heavy rains that have killed at least a dozen people in Peru and now threaten flooding in the capital.

The intense rains and mudslides over the past three days have wreaked havoc around the Andean nation and caught residents by surprise in Lima, a desert city of 10 million where it almost never rains.

A man wades through a flooded street in Lima after the latest round of unusually heavy rains. (Rodrigo Abd/Reuters)

In one of the more dramatic incidents, stunned residents watched and took out cellphone cameras as a woman escaped after being swept into an avalanche of mud, wood debris and farm animals about 53 kilometres south of downtown Lima.

Evangelina Chamorro, 32, had just dropped her two daughters at school and was feeding her pigs with her husband when they were pulled into a landslide. Armando Rivera, Chamorro's husband, told RPP radio they climbed a tree but the trunk broke. They held on to each other's hands but Chamorro eventually lost his grip and got separated.

'There's a person there!'

She emerged near a bridge, lifting herself from a current of wooden planks and walking toward the shore covered head to toe in mud.

"There's a person there!" an onlooker cried out.

Chamorro collapsed as she reached land and was quickly carried by several men to an ambulance. She sustained only minor injuries.

At least a dozen dead as heavy rains cause flooding, wreak havoc 0:18

Authorities said Thursday they expect the rains caused by El Nino, which generates a warming of surface waters in the eastern Pacific Ocean, to continue for another two weeks. Thus far, officials say a total of 62 people have died and 12,000 homes have been destroyed in storms this year.

In Lima, the swelling Huaycoloro River swept away two trucks and threatened to destroy a bridge. Schools nationwide have suspended classes. And seven of the nation's most dangerous criminals were temporarily transported to another facility after a river near the prison threatened to overflow.

President Pedro Pablo Kuczynski said late Wednesday that authorities are prepared to provide shelter and relief to those left homeless.