Thousands of panicked citizens have left a densely-populated district in southern Pakistan following a fresh spell of floods, adding to the growing number of displaced people.

Gushing floodwaters have washed away the first defence line of the Dadu district of southern Sindh province – home to over 1 million people – officials and local media reported on Sunday.

Sindh Chief Minister Murad Ali Shah told reporters that the rescue agencies are trying their best to save the city.

The floodwaters left only one passage for the residents to leave the city as the water level in Manchar Lake, the country's largest freshwater body, is continuously rising.

Footage aired on local TV channels showed thousands of stranded people lodged in tents or under open skies along the main highway that leads to Hyderabad, the second largest district of Sindh after Karachi.

Either side of the highway could be seen inundated in floodwaters for miles.

Another footage showed hundreds of flapped citizens, on mini trucks, wagons, and auto rickshaws, leaving the city. Many others along with their livestock were also spotted trudging along the road under the baking sun.

READ MORE:Millions in flood-hit Pakistan await aid as health crisis unfolds

Over 33 million displaced

The recent downpours – 500 percent higher than average – and massive floods have left 125 million people homeless in Sindh alone, aside from causing a colossal loss of $1.5 billion (Rs350 billion) to agriculture and another $221 million (Rs50 billion) to the livestock.

The severity of the situation also prompted the country's Army Chief Generl Qamar Javed Bajwa to air dash to the literally besieged Dadu city on Saturday evening, directing the troops to accelerate the relief and rescue operations.

Meteorologists heap the blame on climate change, and global warming, which have increased the ferocity, and frequency of the monsoon rains amid fast-melting glaciers.

The current monsoon season that struck the South Asian nuclear country in June, has inundated one-third of Pakistan apart from killing over 1,400 people, according to the country's National Disaster Management Authority.

Over 33 million people of the country's 220 million population have been displaced by the latest downpours and flooding in all four provinces since mid-June, in addition to causing a staggering $30 billion in damages to the already weakened infrastructures.

READ MORE: UN chief: Never seen climate carnage like Pakistan floods