Hundreds of thousands of Pakistanis were fleeing a southern district Friday after the bloated Indus River crushed a levee and flooded new areas, officials said. The UN said as many as 1 million people have been displaced in the south since midweek. In the southern city of Thatta, around 175,000 people – around 70 percent of the city's population – were believed to have packed up and left overnight, said Manzoor Sheikh, a senior government official. Authorities were trying to repair the broken levee and arranging transport for people trying to leave. UN spokesman Maurizio Giuliano said according to reports received by the world body, around 1 million people were displaced in Thatta and Qambar-Shadadkot districts since Wednesday. It is difficult to verify figures given by the authorities, however, partly because of poor or old census data and partly because of the difficulty of tracking migrations over such wide swaths of territory. Many of the areas are hard to reach because of the water, and people may have left their homes well before the evacuation orders. UN aid agencies along with a host of other relief groups have been rushing people and supplies to affected regions as the flooding has lashed Pakistan over the past month. The situation in Sindh “is getting from bad to worse,” Giuliano said. “We are delivering (aid) faster and faster, but the floods seemed determined to outrun our response.” Also at risk in Sindh province are many historic graves, tombs and other sites linked to the Mughal Empire that once ruled the subcontinent. The floods began with the onset of the monsoon and have ravaged a massive swath of Pakistan, from the mountainous north to its agricultural heartland. Almost 17.2 million people have been significantly affected by the floods and about 1.2 million homes have been destroyed or badly damaged, the UN has said.