The police said significant leads have been uncovered.
Hours after PM Narendra Modi held a review meeting to assess the situation in Jammu and Kashmir, police in the Union Territory announced that 50 people have been detained in connection with Sunday's terrorist attack on a bus in Reasi district in which nine people were killed and 41 were injured.
As part of the major crackdown, the search operation to track down the terrorists has been expanded to cover the district's Arnas and Mahore areas which were terrorist hotbeds between 1995 and 2005.
"Significant leads have been uncovered, aiding in the identification and capture of those who may be potentially involved in orchestrating the attack. To ensure a comprehensive probe, search operations have been expanded to cover the far-flung areas of Arnas and Mahore," a police spokesperson was quoted as saying by news agency PTI.
On Sunday, terrorists had opened fire at a 53-seater bus carrying pilgrims from Delhi, Uttar Pradesh and Rajasthan, when it was headed to the Mata Vaishno Devi shrine in Katra from the Shiv Khori temple. The bus plunged into a gorge, killing nine people.
Earlier on Thursday, Prime Minister Narendra Modi chaired a review meeting to take stock of the situation in Jammu and Kashmir. He spoke to Home Minister Amit Shah and newly reappointed National Security Advisor Ajit Doval, and was given a full overview of the situation as well as the counter-terrorism operations being carried out.
Sources told NDTV that the Prime Minister has asked for the "full spectrum of the armed forces' counter-terror capabilities" to be deployed after four terrorist attacks took place in as many days.
Apart from Reasi, terrorists had opened fire in a village in Kathua district on Tuesday. The next day, a policeman was injured in Doda district when a police picket was targeted by terrorists and, earlier, an Army camp was attacked, injuring five Army personnel.
In earlier incidents, there have been times when over 200 people have been detained following a terrorist attack but the challenge before the police and the security establishment is ensuring that they are able to pinpoint the actual perpetrators.
What is worrying security forces is that the attacks have taken place in areas that were known to be free of terrorism. There has been information for some time, however, that Jammu was high on the list of targets of terrorists.
The Reasi Police has also released sketches of two suspected terrorists who could be behind the attack and has announced a reward of Rs 20 lakh for information leading to their arrest.