SRINAGAR, India -- Indian and Pakistani forces traded fire 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.

Pakistan denied initiating the firing, saying its soldiers only responded to the Indian "unprovoked" fire. Islamabad also summoned an Indian diplomat to protest a civilian's killing.

The nuclear-armed nations had recently agreed to stop fire exchanges 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 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 opened a volley of gunfire at them, triggering further exchange, 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 retaliated, and the cross border firing stopped early Wednesday.

In Islamabad, two security officials said Pakistani troops only returned fire after coming under unprovoked fire from the Indian border guards.

The officials said India troops also targeted a village in Pakistani-controlled Kashmir on Tuesday, killing a villager who was grazing cattle in a field near his home. The officials spoke on condition of anonymity as they were not authorized to talk to reporters.

Pakistan summoned an Indian diplomat to protest the "unprovoked cease-fire violation" that killed a civilian. The Foreign Ministry said in a statement that the "deliberate targeting of civilian-populated areas was deplorable" and that cease-fire violations threatened peace and security.

In May, Indian and Pakistani commanders of military operations talked by phone and agreed to defuse tensions in Kashmir. They also agreed to use existing mechanisms of hotline contacts and border flag meetings at local commanders' level to resolve the issues.

Early June, local border guards' commanders on the two sides met along the frontier and reiterated unsuccessfully to stop deadly hostilities.

Tensions have soared in recent months, as both sides have shelled border posts and villages, causing fatalities of soldiers and civilians on both sides. Tens of thousands of villagers have fled homes in dozens of affected villages along the frontier on both sides.

Like in the past, each side has accused the other of starting the hostilities in violation of the 2003 accord.

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-kilometre (125-mile) boundary separating Indian-controlled Kashmir and the Pakistani province of Punjab, where most of the latest fighting has taken place. This somewhat-defined portion, which India refers as "international border" and Pakistan calls "working boundary," is marked by coils of razor wire, watch towers and bunkers that snake across foothills marked by ancient villages, tangled bushes and fields of rice and corn.

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.