A landslide caused by heavy rains after a prolonged drought in La Paz, the capital of Bolivia, flooded dozens of homes early Sunday, local authorities said. It swept away a young girl, spurred evacuations and left parts of the city without electricity.

Torrential rain on Saturday caused a river to spill its banks, dislodging mud from a southwestern La Paz neighbourhood where low-slung, shoddily built dwellings dot the hillside.

The torrent of rocks and soil surged down a narrow ravine early Sunday, wrecking some two dozen homes and flooding another 40, said Juan Carlos Calvimontes, Bolivia's deputy civil defence minister.

"I lost my workshop, and the cars that I had there are buried," said auto mechanic Luis Mencias, his voice shaking as he surveyed the sea of debris.

Hours after the rain subsided, rescuers were still searching for a missing five-year-old girl in the inundated neighbourhood of Bajo Llojeta. Emergency workers trudged through the boot-sucking mud on Sunday, pulling at least six residents — suffering from hypothermia, their hair matted with sludge — from the collapsed hillside. Soldiers helped clear mud from the streets.

"My daughter was with her cousins when the mud came," said Grover Mendoza, the missing girl's father. "The neighbours rescued my nephews, but my daughter was missing."

The mayor of La Paz, Ivan Arias, directly blamed the poor construction of houses perched on the hillside without permits.

"There are irresponsible people who destabilize the hillside and the rains drag it away, affecting the lower-lying neighbourhoods," he said.

In a visit to the site, President Luis Arce delivered aid to flood victims and vowed to hold people responsible for the illegal construction that exacerbated the damage.

"We are shocked by what happened," he said. "This cannot be left like this. An investigation must be carried out."

The city of La Paz, nestled in a valley surrounded by high hills, is particularly prone to floods and landslides. Bolivia's rainy season is just starting after the country suffered one of its most severe droughts in recent memory.