ISTANBUL , Turkey ( CNN ) -- At least 31 people were dead after two days of torrential rains triggered flash floods in northwestern Turkey , sweeping cars into the sea and sending gushing water into homes and businesses , authorities said Wednesday . A Turkish woman awaits rescuers on her balcony following heavy morning rain in Istanbul . Twenty-six people were killed in Istanbul province and five in neighboring Tekirdag province , according to Turkish Prime Minister Recep Tayyip Erdogan . Nine people were feared missing , he said . Among the fatalities in Istanbul were seven female textile workers who were trapped in their minivan , CNN sister network CNN Turk reported . Witnesses in the city of Istanbul said the flash floods hit at 7:30 a.m. Wednesday , washing through an industrial zone situated in a low-lying valley . Dozens of cargo trucks flipped or were ripped to pieces , the wreckage attracting crowds who watched the chaotic scene from nearby hilltops . See photos of the devastation » . At a news conference in Istanbul 's Disaster Management Center , in front of walls of TVs showing live video feeds from Turkey 's largest city , Erdogan expressed condolences to families that lost loved ones during the Muslim holy month of Ramadan . Watch more about the deadly flooding » . He said emergency workers rescued an estimated 1,300 people from the flash floods and pledged billions of Turkish lira for disaster relief in Istanbul and Tekirdag provinces . He also chided developers who built commercial and residential structures in riverbeds that are vulnerable to flooding . `` Our ancestors had a saying : 'The river 's revenge will be heavy , ' `` Erdogan said . `` We should remember what our ancestors said . '' In the wake of this week 's disaster , the prime minister called for relocating all such settlements from riverbeds and moving them to safer ground . Several roads in Istanbul city remained closed , including the airport road , CNN Turk said . Rescue missions were in full swing , with military helicopters whirring overhead . Residents were advised not to wander from their homes . `` We never had such rain in all the time I have been here , '' said Zafer Ercan , deputy mayor of the town of Silivri , an hour west of Istanbul city . View images from iReporters . He said that more than 200 cars were washed into the Sea of Marmara and 800 homes and businesses were flooded in the neighboring town of Selimpasa . The rain stopped Tuesday evening but resumed early Wednesday . Heavy overnight rain flooded western neighborhoods in Istanbul city . The amount of rain that has fallen in two days roughly equals what normally falls in six months in the Turkish province , Istanbul Gov . Muammer Guler told the state-run Anatolia News Agency . CNN 's Ivan Watson and Yesim Comert in Istanbul , Turkey , contributed to this report .
At least 31 killed after torrential rains triggered flash floods in northwest Turkey . 200 cars washed into Sea of Marmara ; 800 homes and businesses flooded . Death toll expected to rise with reports of people being dragged by raging waters .