Flash floods have killed dozens of people and left tens of thousands camped out on higher ground in Vietnam, Cambodia and Thailand, where tourism and farming have suffered millions of dollars in lost revenues and ruined crops, Reuters reported. In Vietnam, floods in the north and the Central Highlands have killed at least 17 in the past week, while unseasonably early floods were expected to reach danger levels in the southern Mekong Delta on Thursday. A storm dumped heavy rains on northern and central provinces last Wednesday, causing floods two days later in the central province of Nghe An, where 13 people, six of them children, were killed, the state-run daily Vietnam News said on Tuesday. Last Friday, two men were swept away by flash floods in the northern mountainous province of Yen Bai, 180 km (110 miles) northwest of the capital, Hanoi. On the same day two farmers working in rice fields were killed by floods in the central highland province of Kon Tum, 540 km (340 miles) north of Ho Chi Minh City. Three children in the eastern Cambodian province of Kompong Cham drowned when strong winds overturned their boat as they evacuated to higher ground. The father of one of the children was also swept away as he tried to rescue them. Disaster officials in Phnom Penh said flood warnings had been posted in three provinces along the Mekong, as workers rushed to build sandbag defences and move people and animals out of low-lying areas. Residents of northern Thailand are still totting up the damage from flooding described as the worst in decades. At least six people have been killed and nine are still missing after flash flooding affected 90,000 people and damaged roads and bridges across six northern provinces, including the northern city of Chiang Mai, a popular tourist destination. Business in the city, which makes about 38 billion baht ($927 million) a year from tourism, has virtually ground to a halt over the past three days under a sea of chocolate brown flood water. Some are estimating the damage at one billion baht ($24.40 million). No tourists have died, although a group of British and Canadian white-water rafters had to be rescued from the Pai river near the Myanmar border town of Mae Hong Son, officials said. "It's the worst flooding in 32 years. I never saw anything like this that caused such damage to houses," Wisoot Buachoom, chief of Mae Hong Son's Tourism Office, told Reuters. --more 1255 Local Time 0955 GMT