Kashmir remained on edge as the authorities stepped up security at vital installations and in sensitive areas, suspended mobile internet services and either "arrested" or "detained" several leaders in fast-paced developments on Sunday night.
Officials said restrictions on movement of people would come into force in Kashmir Valley at the crack of dawn.
The officials said former chief ministers Omar Abdullah and Mehbooba Mufti would not be allowed to move out of their respective house in view of the restrictions, while Congress leader Usman Majid and CPI(M) MLA M Y Tarigami claimed to have been arrested around midnight.
However, no official confirmation of the arrests was immediately available.
"I believe I'm being placed under house arrest from midnight tonight & the process has already started for other mainstream leaders. No way of knowing if this is true but if it is then I'll see all of you on the other side of whatever is in store," National Conference leader Abdullah tweeted.
"To the people of Kashmir, we don't know what is in store for us but I am a firm believer that what ever Almighty Allah has planned it is always for the better, we may not see it now but we must never doubt his ways. Good luck to everyone, stay safe & above all PLEASE STAY CALM," he said in another tweet.
Reacting to the development, Peoples Democratic Party president Mehbooba said, "How ironic that elected representatives like us who fought for peace are under house arrest. The world watches as people & their voices are being muzzled in J&K. The same Kashmir that chose a secular democratic India is facing oppression of unimaginable magnitude. Wake up India."
Responding to Abdullah's tweet, Congress leader Shashi Tharoor said, "You are not alone @OmarAbdullah. Every Indian democrat will stand with the decent mainstream leaders in Kashmir as you face up to whatever the government has in store for our country. Parliament is still in session & our voices will not be stilled."
"What is going on in J&K? Why would leaders be arrested overnight while having done no wrong? If Kashmiris are our citizens &their leaders our partners, surely the mainstream ones must be kept on board while we act against terrorists & separatists? If we alienate them, who's left?" he said in another tweet.
Mobile Internet services have been suspended in Kashmir Valley, the officials said, adding that satellite phones were being provided to police officials and district magistrates.
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The government imposed restrictions under Section 144 CrPC in Srinagar district with effect from midnight.
As per the order, there will be no movement of public and all educational institutions shall also remain closed.
There will be a complete bar on holding any kind of public meetings or rallies during the period of operation of this order.
After the Jammu and Kashmir administration curtailed the Amarnath Yatra and asked pilgrims and tourists to leave the valley at the earliest on Friday, anxious residents continue to throng markets to stock on essentials and serpentine queues have been visible outside shops and fuel stations.
The Anantnag district administration, in view of "panic stocking",ordered all fuel station dealers not to sell petrol or diesel without permission from the district magistrate or an authorised officer.
Various educational institutions in Kashmir Valley also directed their students to vacate hostels.
The authorities in Jammu and Udhampur district also ordered closure of schools and colleges as precautionary measures.
The University of Jammu will remain closed on Monday and all scheduled examinations have been postponed.
The authorities have imposed night curfew in Kishtwar, Rajouri districts and Banihal area of Ramban district.
Additional paramilitary forces, which arrived in Kashmir in the past few days, have been deployed across the city and in other vulnerable areas of the valley, the officials said.
The strength of the security personnel has been increased around vital installations such as the civil secretariat, police headquarters, airport and various central government establishments in the city, they said.
Barricades have been erected on many arterial roads, including the entry and exit points to Srinagar, the summer capital of the state.
Riot control vehicles have also been kept on standby in some areas where apprehension of law and order disturbances is more, the officials added.
In Delhi, Union Home Minister Amit Shah held a meeting with top security officials on Sunday and is believed to have discussed the prevailing situation in Jammu and Kashmir, officials said.
The hour-long meeting was attended by National Security Advisor Ajit Doval, Union Home Secretary Rajiv Gauba and other senior officials.
Political parties in J-K had expressed apprehensions about such action after the Centre deployed additional troops and curtailed the Amarnath Yatra.
Jammu and Kashmir Governor S P Malik had earlier dismissed speculations that the Centre might be planning to do away with Article 35A of the Constitution, which gives exclusive rights to the state's residents in government jobs and land.
The parties on Sunday unanimously resolved to fight any attempt to abrogate the constitutional provisions that guarantee it special status or any move to trifurcate the state or "unconstitutional delimitation", NC leader Farooq Abdullah said.
The meeting was also attended by Mehbooba, Omar Abdullah, Taj Mohiuddin (Congress), Muzaffar Beig (PDP), Sajad Lone and Imran Ansari (Peoples Conference), Shah Faesal (J&K Peoples Movement) and M Y Tarigami (CPI-M).