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.

Also Friday, hundreds of people rallied in Muzaffarabad, the capital of Pakistan-administered Kashmir, to denounce the suspension of the water-sharing treaty.

The demonstrators chanted slogans against Indian Prime Minister Narendra Modi and burned his effigy before dispersing peacefully. Similar small rallies were also held elsewhere.

Pakistan’s Senate condemned the attack, while passing a resolution denouncing New Delhi’s attempt to link Islamabad to it and the suspension of the water treaty.

Hundreds of demonstrators also took to streets in India’s capital of New Delhi, where most markets were shut in protest against the killings. They demanded action against Pakistan.

“Now our patience has run out,” protester Surekha Sharma said. “Now we want revenge for this.”