At least 13 people have died in floods after unusually heavy rains hit Tanzania's main city of Dar es Salaam.The Tanzania Meteorological Agency (TMA) has warned that the downpours are set to continue and has told those living in the city's valleys to move.The BBC's Aboubakar Famau in Dar es Salaam says the city's business activities have come to a standstill.Several main roads that link the centre to the suburbs are flooded and some bridges have been destroyed.Refusing to move According to TMA, these are the heaviest rains Tanzania has experienced since independence in 1961.Hundreds of people living in the city's valleys have been left homeless.Taabu Kibwa said her whole house was covered by water."We have lost all our properties, in fact we are left with empty hands. Everything in the house has been lost including television sets and refrigerators," she told the BBC."I have three children, one of whom I don't even know where he is."Another resident, Shaaban Ramadhan Hussein, said he worked and lived in his home which was now under water."Everywhere is flooded, people are on top of their house roofs, no rescue has come so far. We are not happy, it is like the government doesn't care about us," he said.Our correspondent says the floods seem to have caught many by surprise, yet it was only a few days ago that the Tanzania Meteorological Agency warned of possible devastation by heavy rains.The police commander for Dar es Salaam, Suleiman Kova, has urged people to leave the valleys, but he said some residents were refusing."We went [to] rescue some and they then refused to vacate saying they are keeping an eye on their properties," he said.Our correspondent says the government has set up centres to temporarily accommodate people displaced by the floods.There is little chance of them relocating to their home villages or regions before the festive season because the weather agency has cautioned that the rains are not going away, he says."We have been having heavy rainfall the day before yesterday, yesterday and today - we will therefore have more floods," said Agness Kijazi, TMA's director.