Hundreds of houses on Saturday were flattened, communications disrupted, roads blocked by mudslides, and water and electricity supplies interrupted across the Himalayan region.
Information Minister S Jaipal Reddy said the death toll in Indian-administered Kashmir neared 300, including civilians and army personnel, the AFP news agency reported.
The Uri area, close to the Line of Control, the border that splits the disputed state between Indian and Pakistani administered parts, bore the brunt of the earthquake.
Among the dead were 32 soldiers, most of whom were buried alive when their bunkers collapsed.
"Destruction is massive in Uri, which falls close to the epicentre of the quake," an Indian army official said.
"Initial reports are that not many houses are standing in the area."
As Uri and several other parts of north and northwestern Kashmir have been cut off from the rest of the world, officials warned that the final toll would be "very high".
Urosoo village, in Uri district, has been almost wiped out. As many as 40 people lost their lives in this tiny village along the Srinagar-Muzaffarabad road. At least 50 people were killed and 120 wounded in the Karnah area of neighbouring Kupwara district.
In northwestern Baramulla district more than 500 houses and other buildings were razed or damaged. In Uri 70% of the houses have been destroyed. In the Teetwal area of Kupwara district, also close to the Line of Control, 98% of houses have caved in or been damaged. The woods at Baderhar, Kupwara, are on fire.
A number of religious and historic monuments have been damaged, including the main minaret of the Hazratbal shrine in Srinagar too was damaged.
The Indian army set up a field hospital in Uri. Many makeshift medical facilities are treating the injured, said chief secretary Vijay Bakaya.
"Destruction is massive in Uri, which falls close to the epicentre of the magnitude quake. Initial reports are that not many houses are standing in the area"
Indian army official
The last tremor was felt at 4.16pm (1045 GMT) on Saturday.
Amid aftershocks, people in the capital, Srinagar, have moved into open spaces to offer special prayers.
People could be seen praying in the streets and reciting verses from the holy Quran.
Mosque loudspeakers were used to call on people to increase prayer and assist those in need.
"We must pray for our brethren who have passed away today and thank Allah [God] for having saved us," the imam of Ilahi Bagh mosque on the outskirts of Srinagar told 300 men and children before leading them in a thanksgiving prayer.
The city's government-run SMHS hospital received 270 people, either injured or in a state of shock, within the first two hours of the first tremors felt at 9.24am.
"People have suffered injuries, but most are being treated for palpitations and shock," said doctor Anwar Talib Hussein.
Hundreds of buildings have been weakened, and residents and employees have refused to return to apartments and buildings.
Schools and other educational institutions have also been closed.
At least one school building in Srinagar collapsed. "Luckily, the school remains closed at the weekend," said a police official.
The 294km Srinagar-Jammu highway, the only road between the Vale of Kashmir and the rest of India, has been closed by landslides at Siraj area in Ramban belt.
In Uri, too, the quake triggered landslides, sending two buses and their passengers into a gorge.
Terrified crowds filled the streets,
fearful of returning home
The quake cut off villages and the 170km Srinagar-Muzaffarabad road.
An official said information about some areas was lacking because of communications had been disrupted.
"The telephone and other communications have been snapped completely, and whatever information we have is what we are being told, either by police or the army," said BB Viyas, divisional commissioner, the region's top civilian official.
"We've flashed messages to all the 14 district magistrates and their replies are awaited."