A massive manhunt is underway in India to find the attackers who killed 26 people in India-controlled Kashmir, as world leaders including Anthony Albanese express their support.
Another 17 people were injured when four armed militants shot at tourists in the scenic Baisaran valley in the popular holiday area of Pahalgam in the Himalayas, known as "Little Switzerland".
It was the deadliest attack on civilians in India since the 2008 Mumbai terror attacks.
All 26 people killed were men and all were Indian nationals except one who was Nepalese.
Shortly after the incident, Mr Modi said those responsible for the "heinous act" would "be brought to justice".
He cut short his visit to Saudi Arabia and returned to New Delhi on Wednesday, local time, holding a meeting with his national security advisor, foreign minister and senior officials at the airport.
US President Donald Trump also called Mr Modi to offer "full support to India to bring to justice the perpetrators of this heinous attack".
The attack coincided with a trip to India by US Vice-President JD Vance and his family.
Indian Defence Minister Rajnath Singh said "there will be a loud and clear response soon."
"We will not only reach those who have perpetrated this incident but also those who, sitting behind the scenes, have conspired to commit such acts on the soil of India," Mr Singh said.
He did not identify those he believed were responsible for the killings, but said that "India's government will take every step that may be necessary and appropriate".
"We are concerned at the loss of tourists' lives," Pakistani foreign ministry spokesperson Shafqat Ali Khan said in a statement.
"We extend our condolences to the near ones of the deceased and wish the injured a speedy recovery."
Australian Prime Minister Anthony Albanese has called for the attackers to be "held to account".
Mr Albanese said he spoke to India's Prime Minister Narendra Modi "to offer my condolences on behalf of Australia following the terrorist attack in Jammu and Kashmir".
"The horrific loss of life on innocent civilians is an act of senseless violence which has shocked the world. Those responsible must be held to account," Mr Albanese said in a statement.
"Australia and India are great friends and we stand with India at this time."
India's foreign ministry announced on Wednesday that the main land border with Pakistan would close following the attack.
Indian Foreign Secretary Vikram Misri told a media briefing that the cross-border linkages of the attack had been "brought out" at a special meeting of the security cabinet, after which it was decided to act against Pakistan.
Mr Misri said the main border crossing between the two countries will be closed with immediate effect and Pakistani nationals will not be allowed to travel to India under special visas.
In a further deterioration of relations between the two countries, several top Pakistani military advisors have also been told they have a week to leave New Delhi.
After India's announcements, Pakistan confirmed it's National Security Committee would meet on Thursday, local time, to determine how to respond.
Deputy prime minister Ishaq Dar, who is also the foreign minister, confirmed the move on X.
The committee comprises of senior military and civil officials and only convenes in times of external threat or major terror attack.
Tourists leave Kashmir
The BBC reported that among those killed was a man on his honeymoon.
Asavari Jagdale, from India's western state of Maharashtra, lost her father and uncle in the attack.
She told local media that she and her family hid inside a nearby tent along with other tourists when the shooting started.
When the militants reached their tent, Asavari said they asked her father, Santosh Jagdale, to come out and recite an Islamic verse.
"When he failed to do so, they pumped three bullets into him, one on the head, one behind the ear and another in the back," she said. "My uncle was next to me. The terrorists fired four to five bullets into him."
Tourists scrambled to leave the area a day after the attack, cramming into buses and taxis, while hoteliers reported a surge of cancellations.
At Pahalgam, the usually tranquil meadows surrounded by pine forests and snow-capped mountains, reverberated with the thumping sounds of military helicopters taking part in a vast manhunt for the attackers.
Smears of blood were still visible at the site of attack, now patrolled by soldiers dressed in bulletproof jackets.
Soldiers guarded the entrance, as forensic investigators collected evidence.
For New Delhi, the 3.5 million tourists who it says visited Kashmir in 2024 illustrated what officials called "normalcy and peace" returning to the troubled region after a massive crackdown.
Rebels in the Muslim-majority region have waged an insurgency since 1989, seeking independence or a merger with Pakistan.
The fighting has killed tens of thousands of people, but violence had dropped since New Delhi revoked Kashmir's limited autonomy in 2019.
[MAP]The decision to split the state into two federally administered territories, Jammu and Kashmir, and Ladakh allowed outsiders to move in, gain jobs and buy land, but upset Pakistan.
Both countries claim the area in its entirety, but the region is ruled in part by Hindu-majority India and Islamic Pakistan.
The two countries have fought three wars over the area since it was partitioned by the British in 1947.
India has an estimated 500,000 soldiers permanently deployed in the territory.
Hunt for attackers continues
A little-known militant group, the "Kashmir Resistance," claimed responsibility for the attack in a social media message, expressing discontent that more than 85,000 "outsiders" had been settled in the region, spurring a "demographic change".
In a fresh statement on Wednesday, local time, the group said that the "individuals targeted were not ordinary tourists; instead, they were linked to and affiliated with Indian security agencies" and said it would step up its activities.
India's government has not commented on the group's claims, which could not be independently verified.
Indian security agencies say the group, also known as The Resistance Front, is a front for Pakistan-based militant organisations such as Lashkar-e-Taiba (LeT) and Hizbul Mujahideen.
[THE WORLD IV]Security analyst Kabir Taneja told ABC's The World he agreed with that assessment.
"The main idea is that they minimise the linkages that they have with groups back inside Pakistan, while continuously maintaining financial and ideological linkages while conducting these attacks," Mr Taneja said.
"Kashmir has been looking at level and semblance of normalcy for quite some time now.
"The main idea is to cause chaos and deliver a setback to any kind of economic and political normalcy that Kashmir might have been looking forward to."
Pakistan Army chief General Asim Munir described Kashmir as the "jugular vein" of his country less than a week before the deadly attack.
Mr Taneja said "it may not be a coincidence" that the attack followed shortly after his speech.
"How Pakistan views India has never changed and is not bound to change any time soon," he said.
"A lot of these terror attacks do attach to ecosystems inside Pakistan which are state-supported.
"Unless there is an inherent policy change and a change of view on India inside Pakistani politics and society, this is a situation of continuation."
India has previously accused Pakistan of supporting militant groups to launch attacks in the area.
Pakistan has always denied the claim, saying it only supports Kashmir's struggle for self-determination.
ABC/wires
