Heavy rains have left a trail of destruction in Rio de Janeiro, killing at least 10 and leaving streets soaked with so much water rescue workers are swimming along roads in the Brazilian city.

Torrents of water gushed down streets, sweeping up cars and uprooting trees after rains that began on Monday evening.

The downpours slowly weakened by Tuesday evening, although mayor Marcelo Crivella said the city was still in “crisis” mode, the highest of three official emergency levels.

Officials said six inches of rain fell in just four hours on Monday night, more than the average for the whole month of April.

Local television stations showed firefighters in that neighbourhood wading through knee-deep water pulling a small boatload of children evacuated from a school bus on a flooded street.

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Photographs showed emergency workers swimming along a highway in order to reach a submerged car.

Sirens sounded in 20 flood-prone areas of the city, alerting people to make their way to pre-established safe spaces.

However, no alarm was given in the Babilonia slum, which sits on a hill behind the iconic Sugarloaf Mountain.

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The fire department said two women there died in a mudslide – leading local residents to complain about the lack of warning.

Mr Crivella, acknowledging the city’s lack of preparedness for the deluge, said sirens did not sound in Babilonia because the water had not reached the minimum threshold to activate the alarms.