India said Monday it had returned fire after “unprovoked” small arms attacks from Pakistan along the de facto Kashmir border for the fourth straight night, as tensions escalate following last week’s deadly assault on tourists in the region.

The April 22 attack, which killed 26 people, has inflamed relations between the two nuclear-armed neighbors. Indian authorities identified two of the three suspected militants as Pakistani nationals, though Islamabad has denied any involvement and called for an independent investigation. According to security officials and survivors, the assailants separated the victims by name and targeted Hindus before shooting them at close range in a meadow near Pahalgam.

The massacre has provoked national outrage in Hindu-majority India, sparking demands for action against Islamic Pakistan, which New Delhi accuses of funding and harboring terrorism in the disputed Kashmir region. In the aftermath, both countries have enacted retaliatory measures, including India’s suspension of the Indus Waters Treaty and Pakistan’s closure of its airspace to Indian airlines.

China, which maintains ties with both nations, urged restraint and welcomed efforts to ease tensions.

The Indian Army said it responded to “unprovoked” gunfire originating from several Pakistan Army posts around midnight on Sunday along the Line of Control (LoC), a 740-kilometer (460-mile) stretch dividing Indian- and Pakistani-administered Kashmir. No casualties were reported. Pakistan’s military has not commented on the exchange.

Separately, Pakistan’s army reported killing 54 Islamist militants attempting to cross from Afghanistan into Pakistan over the past two days.

India has also ramped up security operations since the Kashmir attack. While some military exercises were described as routine drills, a defense official confirmed heightened readiness measures were in place.

Local police in Indian Kashmir said roughly 500 individuals have been detained for questioning after security forces conducted sweeping searches across nearly 1,000 homes and forested areas. At least nine houses have been demolished as authorities intensify their hunt for those linked to the attack.