Updated

Indian and Pakistani forces were firing along the highly militarized frontier in disputed Kashmir early Wednesday after Pakistani firing killed at least four Indian paramilitary soldiers and injured three others on border patrol, Indian officials said.

The nuclear-armed nations had recently agreed to stop trading fire along the volatile frontier and uphold a cease-fire accord dating back 15 years.

Indian border guards said Pakistani soldiers first targeted a soldier around midnight by a sniper fire as the Indian soldiers patrolled a border area in the Jammu region.

As other soldiers tried to rescue their fallen comrade, Pakistani soldiers fired volley of gunfire at them, triggering exchange of gunfire, two border officials said. The two, who spoke on condition of anonymity in keeping with border guards policy, said three soldiers were killed on the spot while the other died later while being evacuated.

They said Indian soldiers were retaliating, and the cross border firing was ongoing.

Pakistan did not immediately comment.

India and Pakistan have a long history of bitter relations over Kashmir, which both claim. They have fought two of their three wars since 1947 over their competing claims to the region.

This year, soldiers from the two nations have engaged in fierce border skirmishes along the rugged and mountainous Line of Control, as well as a lower-altitude 200-kilometer (125-mile) boundary separating Indian-controlled Kashmir and the Pakistani province of Punjab, where the latest fighting occurred.

The fighting has become a predictable cycle of violence as the region convulses with decades-old animosities over Kashmir, where rebel groups demand that the territory be united either under Pakistani rule or as an independent country.

India accuses Pakistan of arming and training anti-India rebels and also helping them by providing gunfire as cover for incursions into the Indian side.

Pakistan denies this, saying it offers only moral and diplomatic support to the militants and to Kashmiris who oppose Indian rule.

Rebels have been fighting Indian rule since 1989. Nearly 70,000 people have been killed in the uprising and the ensuing Indian military crackdown.