Thrissur – Rescuers waded into submerged villages in southern India on Sunday in a desperate search for survivors cut off for days by floods that have already killed more than 350 people.Entire villages in Kerala have been swept away in the state's worst floods in a century, and emergency responders fear the death toll will rise as they reach areas almost entirely underwater.In Thrissur, one of the worst-hit districts, rescuers sifting through inundated houses have discovered the bodies of those unable to escape as the floodwaters quickly rose."They didn't think that it would rise this high – 10 to 15 feet at some places – when the initial warnings were issued," said Ashraf Ali K.M, who is leading the search in the small town of Mala."Some of them later gave distress calls when the water rose high and fast," he told AFP at the scene, where dead cattle and other livestock floated past.Thousands of army, navy and air force troops have fanned out across Kerala to assist as distress calls sound out across the idyllic tourist hotspot.The death toll stands at 357, local officials said, with 33 killed in just the last 24 hours.Among the dead was a mother and son in Mala, whose home collapsed around them late on Saturday.Another was a local man who volunteered for the search and rescue mission.His body was retrieved by comrades early on Sunday, said Dibin K.S, a Kerala firefighter, in a grim reminder of the perils facing rescuers.Officials say many houses are irreparably damaged across the state, and have warned residents against trying to return to them.Panicked appealsRoads and 134 bridges have been damaged, isolating remote areas in the hilly districts of the state which are worst affected.With power and communication lines down, thousands remained trapped in towns and villages cut off by the floods amid growing shortages of food and water.A train from Pune, in Maharashtra state, embarked south on Saturday for Kerala laden with one million litres of drinking water.Panic-stricken flood victims have been making appeals on social media for help, saying they cannot get through to rescue services.In Mala, villagers in desperate wait had to improvise as the floodwaters rose.Jobin K John, a local rescuer, showed pictures of locals rowing through the murky brown waters using kitchen pots as rafts to reach their stricken neighbours."They used these huge cooking pots to rescue around 100 people in the first wave of flash floods, as no one was prepared (for a rescue)," he told AFP.Entire villages wiped outMobile phone operators have been offering free data and SMS messages across Kerala since Saturday to assist with distress calls.Dam levels remain dangerously high, swollen by monsoon deluges.More than 321 centimetres of rain has fallen on the hilly central district of Idukki, which is now virtually cut off from the rest of the state.Landslides triggered by the torrential downpours have wiped out entire villages. Some 350 000 people have been left homeless and taken shelter in relief camps.The floods have caused an estimated $3bn in damage, but the bill is likely to rise as the scale of devastation becomes clearer."Actual losses can be estimated only after the water recedes," Kerala's state information officer said in a statement on Sunday.The state chief minister has requested extra funding as well as 20 more helicopters and 600 motorised boats in order to step up the rescue efforts.Indian Prime Minister Narendra Modi conducted a brief air inspection tour of the state on Saturday and announced an immediate grant of $75m.