ILOILO  - Flash floods and landslides triggered by Typhoon Fengshen left at least 19 people dead in the Philippines, while an overflowing dam stranded tens of thousands on rooftops, officials said Saturday. At least 30,000 people living in Iloilo in the central Philippines had scrambled onto rooftops fleeing the rushing water after the man-made dam overflowed, said the city's acting mayor Jed Mabilog. Rescuers have reported that many could be missing or killed, though this could not be independently confirmed, he said. "I have received a lot of text messages appealing for helicopters, there are many people trapped on the rooftops," Iloilo congressman Serg Biron told DZBB radio. "This is the worst flooding that has hit Iloilo in history." Fengshen, upgraded from a tropical storm on Friday, swept through the country's center over the weekend, unleashing torrential rains, causing power outages and forcing the evacuations of hundreds of thousands of people. Officials said earlier that flash floods and landslides triggered by the typhoon had left at least 19 people dead. In the urban centres of Jaro and Iloilo, residents waded through waist-high waters that made roads impassable to vehicles. The National Power Corporation was forced to shut down its power plant in the area, triggering a blackout across the province, plant manager Nelson Hemona said. Roads connecting the southern cities of Cotabato and General Santos on Mindanao island were flooded, while a concrete bridge also collapsed, isolating some villages and towns, Catholic-run radio station DXMS reported. The storm forced more than 200,000 people to seek temporary shelter in the eastern Bicol region, the civil defence office said. Heavy rains battered the Bicol region overnight, and more than 600 people were stranded in various seaports there. Fengshen also uprooted small trees, blew away tin roofs and caused power outages in the central Visayas provinces. At 5:00 pm (0900 GMT) on Saturday, Fengshen was tracking northwest, packing winds of 195 kilometres an hour as it headed towards Mindoro province. It was forecast to dump heavy rain over large swathes of the central Visayas region and parts of the main island of Luzon through Sunday, the weather bureau said. Residents in low-lying areas and near mountain slopes were warned about possible flash floods and landslides, while those in coastal areas were cautioned about big waves. Officials said domestic flights to the central Philippines have been suspended, while inter-island ferry services were also halted. Government agencies were instructed to stockpile relief goods and state-run hospitals were put on alert. President Gloria Arroyo ordered a crackdown on profiteers and hoarders of basic commodities, especially rice, in areas hit hard by the typhoon. In a statement late Saturday, shortly before she left on a 10-day visit to the United States, she said Agriculture Secretary, Arthur Yap, has been ordered to ensure stable rice supplies in affected areas. "If Frank (the local name for Fengshen) will bring flood, Art (Arthur) will respond by flooding these areas with rice," she said. "If they will exploit the situation, hoarders will soon find themselves in hot water," she said. Arroyo met with the National Disaster Coordinating Council (NDCC) and she said the government would do everything it could to get relief to the affected areas.