SRINAGAR, India — Indian and Pakistani soldiers briefly exchanged fire along their highly militarized frontier in the disputed Himalayan region of Kashmir, Indian officials said Friday, as tensions soared between the nuclear-armed rivals following a deadly attack on tourists.

India has described the massacre in which gunmen killed 26 people, most of them Indian, as a “terror attack” and accused Pakistan of backing it. Pakistan denied any connection to the attack near the resort town of Pahalgam in India-controlled Kashmir. It was claimed by a previously unknown militant group calling itself the Kashmir Resistance.

With the region on edge, three Indian army officials said that Pakistani soldiers fired at an Indian position in Kashmir late Thursday. The officials, who spoke on condition of anonymity in keeping with departmental policy, said Indian soldiers retaliated and no casualties were reported.

Pakistan’s Ministry of Foreign Affairs declined to comment on the report.

Tuesday’s attack in Kashmir was the worst assault in years targeting civilians in the restive region. On Wednesday, India suspended a crucial water-sharing treaty that has withstood two wars between the countries and closed their only functional land border crossing. A day later, India revoked all visas issued to Pakistani nationals with effect from Sunday.

Pakistan responded angrily that it has nothing to do with the attack, and canceled visas issued to Indian nationals, closed its airspace for all Indian-owned or Indian-operated airlines and suspended all trade with India.