A sudden wave of flood waters swamped hundreds of villages in the region, destroying houses, farmland and roads, forcing thousands of people to take shelter on high ground, in government buildings and schools.
Three people, including one child, were buried in mudslides and three others were washed away by fast flowing waters in two northeastern mountainous states of Meghalaya and Arunachal Pradesh, police said.
In the oil- and tea-rich state of Assam, around 70,000 people have been affected by flash floods, as authorities called rescue workers to evacuate stranded people.
Officials said heavy rains and later the release of excess water from dams by power generating companies in Arunachal Pradesh and neighbouring Bhutan caused flooding in the region.
"It all started overnight and we are trying to shift the people to safer places," said Hemkanta Pegu, a local civil servant in Assam's Lakhimpur district.
Though officials set up temporary shelters for the homeless in schools and government buildings, many people have camped on highways under plastic sheets with whatever little they had salvaged of their belongings.
The regional weather office warned of more showers in the next 48 hours in the region.
Floods and landslides are common in the mountainous northeast during the annual monsoon season that normally begins in June and continues through September.
In India, more than 200 people have been killed in rains in this year, 30 of them in the northeast.
Assam accounts for about 55 percent of India's tea production and also produces oil. Officials said the rains had not affected tea trade or oil exploration. (Reporting by Biswajyoti Das, Editing by Matthias Williams)
- Reuters - Thomson Reuters Foundation
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