The worst monsoon flooding in a century has killed 350 people and displaced 800,000 in India’s southwestern Kerala state, racking up storm damages the national government already estimates at nearly $3 billion.

“We’re witnessing something that has never happened before in the history of Kerala,” said Chief Minister Pinarayi Vijayan. “The Kerala government said many of those who died had been crushed under debris caused by landslides,” the BBC states.

“The downpours that started August 8 have triggered floods and landslides and caused homes and bridges to collapse across Kerala, a picturesque state known for its quiet tropical backwaters and beautiful beaches,” The Associated Press reports. “Thousands of rescuers were continuing efforts to reach out to stranded people and get relief supplies to isolated areas by hundreds of boats and nearly two dozen helicopters.”

Since the downpours began, at least 250 have died in Kerala, and “more than 1,000 people have died in flooding in seven Indian states since the start of the monsoon season.” Local officials said the rainfall in some areas was more than double the usual monsoon volume.

Floodwaters in some regions reached three metres. “In several villages in the suburbs of Chengannur, one of the worst-affected areas, carcasses of dead cattle were seen floating in muddy waters as water began receding,” AP notes. “Vast rice fields continued to be marooned, and many vehicles were submerged.”

“The severe rains have engulfed entire villages, caused landslides, and thrown open dam gates. The military has deployed hundreds of troops to help the state with rescue victims,” the New York Times adds. “Helicopters airlifted stranded families from the rooftops of their homes, and the navy plucked survivors desperately clutching tires and other floating debris from the fetid waters.”

At least eight people died when an irrigation dam burst, and the Kerala government urged residents to heed evacuation warnings after 80 of the state’s dams reached what the Times calls “precarious levels”.

Parts of the region’s commercial capital, Cochin, are underwater. With 10,000 kilometres of roads damaged and at least one airport closed until August 26, relief efforts were focused in part on bringing 1.5 million litres of drinking water to the affected area by rail.

Prime Minister Justin Trudeau tweeted his concern about the disaster, and Canadians with connections to the region worried about friends and relatives left stranded, CBC notes. “No one was prepared for this,” said Prasad Nair, president of the Mississauga Kerala Association. “Most people have lost everything they have.”

Nair, who came to Canada in 2003, said his organization was pushing for an appointment with Trudeau’s office to arrange support for the rebuilding effort. “Canada has the technology, ability, and experience in these kinds of disaster operations,” he said.

“It is normal for Kerala to get some of the country’s highest rainfall during monsoon season, but the India Meteorological Department said it had been hit with 37% more than usual because of a spell of low pressure over the region,” the BBC notes. “Environmental scientists are also blaming deforestation, especially the failure to protect ecologically fragile mountain ranges in the area.”