Indian security forces in Jammu and Kashmir (J&K) were conducting a major manhunt yesterday, a day after gunmen opened fire on tourists and killed 26 people in the region's worst attack on civilians in a quarter of a century.

J&K Chief Minister Omar Abdullah reported an "exodus of our guests", as tourists scrambled to leave, cramming into buses and taxis, while hoteliers reported a surge of cancellations.

At Pahalgam, the site of the attack, the usually tranquil meadows surrounded by pine forests and snowcapped mountains, reverberated with the thumping sounds of military helicopters taking part in a vast manhunt for the attackers, reports AFP.

Around 24 hours after the attack that also left 17 people injured, 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. All those killed were listed as residents of India except one man from Nepal, reports AFP.

India's Defence Minister Rajnath Singh said that those who carried out and planned the Kashmir region's worst attack on civilians in years would see a swift response.

A little-known militant group, the "Kashmir Resistance," claimed responsibility for the attack in a social media message. It expressed discontent that more than 85,000 "outsiders" had been settled in the region, spurring a "demographic change".

In a fresh statement yesterday, the group said that the "individuals targeted were not ordinary tourists; instead, they were linked to and affiliated with Indian security agencies".

Indian security agencies say Kashmir Resistance is a front for Pakistan-based militant organisations such as Lashkar-e-Taiba and Hizbul Mujahideen. Pakistan has said it only provides moral and diplomatic support to the insurgency in Kashmir.

Hundreds of security forces rushed to the Pahalgam area soon after the attack and a massive combing operation was launched in the forests there, two security sources told Reuters. About 100 people suspected to have been militant sympathisers in the past were called to police stations and questioned, they added.

Police also released sketches of three of the four suspected attackers.

"We are concerned at the loss of tourists' lives," Pakistani foreign ministry spokesman 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," Khan added.