At least 17 people were reported dead after the most powerful storm to strike India in 14 years made landfall causing widespread damage.
Al Jazeera's Karishma Vyas, reporting from the Indian capital New Delhi, said the cyclone appeared to have caused "large-scale" destruction in the states of Odisha and Andhra Pradesh but that early warning system are being credited with helping avoiding a major catstrophy.
More than 800 thousand people were evacuated from their homes in advance of its arrival on Saturday evening.
Mud huts have been washed away as have rice crops, power and communication lines and rail links. The storm is affecting more than 10 million people, up to a hundred kilometres inland.
Heavy rains predicted
Phailin had slowed significantly overnight, but meteorologists were predicting heavy rains across Odisha.
"Its intensity is still strong, but after crossing the coast it has weakened considerably," Sharat Sahu, a senior official with the state's Indian Meteorological Department, said.
Storms typically lose much of their force when they hit land, where there is less heat-trapping moisture feeding energy into the storm.
In Brahmapur in Odisha, about 10km inland from where the eye of the cyclone struck, there were no reports of deaths early on Sunday morning.
|Cyclone Phailin is only the latest in a long series of storms to have struck India's east coast from the Bay of Bengal [AFP]
But the storm had wrought havoc on the small town, with the wind shattering windows, blowing down trees and electrical poles and terrifying residents.
In Bhubaneshwar, the state capital, billboards and traffic lights had fallen across the city and trees were uprooted, but early reports indicated the state capital escaped major damage.
With most communications down, and many roads impassable because of fallen trees, there was no news at all yet from many coastal towns and villages.
Officials in both Odisha and Andhra Pradesh had been stockpiling emergency food supplies and setting up shelters.
Al Jazeera's Faiz Jamil, reporting from Srikakulam in Andra Pradesh, said that the destruction of crops would have huge implications not only for the farmers but food supply in India.
The Indian military put some of its forces on alert, with lorries, transport planes and helicopters at the ready for relief operations.
Electric utility authorities in Odisha had switched off the power in 12 districts in the path of the cyclone after scores of electric pylons had toppled from the torrential rain and high winds.
With some of the world's warmest waters, the Indian Ocean is considered a cyclone hot spot, and some of the deadliest storms in recent history have come through the Bay of Bengal, including a 1999 cyclone that also hit Orissa and killed 10,000 people.
US forecasters had repeatedly warned that Phailin would be immense, and as the cyclone swept across the Bay of Bengal towards the Indian coast on Saturday, satellite images showed its spinning tails covering an area larger than France.
By Saturday evening, more than 500,000 people had been moved to higher ground or shelters in Odisha, and 100,000 more in neighbouring Andhra Pradesh, officials said.
LS Rathore, the head of the Indian Meteorological Department, forecast a storm surge of 10-11.5ft but several US experts had predicted that a much higher wall of water would blast ashore.
The height of the surge, though, remained unclear on Sunday morning.
The 1999 Odisha super cyclone - similar in strength to Phailin but covering a smaller area - threw out a 19ft storm surge.