Residents waded through waist- and knee-deep water in several parts of the Assam state capital, Gauhati, which was hit by nearly 60 millimeters (2.3 inches) of pounding rain on Thursday night. The average four-month monsoon rainfall is 89 centimeters (35 inches).
"Inflatable boats and makeshift banana rafts have become a mode of transport in the heart of Gauhati. This is something I didn't imagine," said Rani Das, a researcher who could not reach her office on Saturday.
Loose patches of earth rolled down the hills around Gauhati as light rain continued on Saturday. Authorities closed schools for the day in the city.
India's Meteorological Department said the rains were caused by a strong monsoon, while other parts of the country were experiencing 30 to 40 percent deficiency in rainfall in June. India's monsoon season lasts from June to the end of September.
All the 11 deaths in the past two days have been reported from Gauhati. Police said they included a family of three who were buried when a portion of a concrete house caved in on their tin-roofed home early Friday. Another person died in a mudslide and five others were electrocuted.
Chief Minister Tarun Gogoi, Assam state's top elected official, waded through the deluge to reach some of the worst-hit areas, but was booed by residents angry over the lack of food and drinking water.
Elsewhere in Assam state, monsoon rain fed the mighty Brahmaputra and other rivers, flooding at least six of the state's 27 districts, including vast swathes of crop area.