India attacked Pakistan and Pakistani Kashmir on Wednesday and Pakistan said it had shot down five Indian fighter jets in the worst fighting in more than two decades between the nuclear-armed enemies.

The Indian hits on targets in Pakistan’s most populous province of Punjab were the first since their last full-scale war more than half a century ago, triggering fears of a further escalation of military hostilities.

India said it struck nine Pakistani “terrorist infrastructure” sites, some of them linked to an attack by Islamist militants on Hindu tourists that killed 26 people in Indian Kashmir last month.

India had earlier said two of three suspects in that attack were Pakistani nationals but had not detailed any evidence. Pakistan denied that it had anything to do with the killings.

Islamabad said six Pakistani locations were targeted, and that none of them were militant camps. At least 26 civilians were killed and 46 injured, a Pakistan military spokesperson said.

Indian forces attacked facilities linked to Islamist militant groups Jaish-e-Mohammed and Lashkar-e-Taiba, two Indian military spokespersons told a briefing in New Delhi.

The strikes targeted “terrorist camps” that served as recruitment centres, launchpads, and indoctrination centres, and housed weapons and training facilities, the spokespersons said.

They said Indian forces used niche technology weapons and carefully chose warheads to avoid collateral damage to civilians and civilian infrastructure, but did not elaborate on the specifics or methods used in the strikes.

“Intelligence and monitoring of Pakistan-based terror modules showed that further attacks against India were impending, therefore it was necessary to take pre-emptive and precautionary strikes,” Indian Foreign Secretary Vikram Misri, the top official in its external affairs ministry, told the briefing.

The joint briefing by the Indian military and foreign ministry listed past attacks in India blamed on Pakistan, with Misri saying Pakistan had not done anything to “terrorist infrastructure” there after the attack on Kashmir tourists.

Pakistan said Indian missiles hit three sites and a military spokesperson told Reuters five Indian aircraft had been shot down, a claim not confirmed by India.

However, four local government sources in Indian Kashmir told Reuters that three fighter jets had crashed in separate areas of the Himalayan region during the night.

All three pilots had been hospitalised, the sources added. Indian defence ministry officials were not immediately available to confirm the report.

Images circulating on local media showed a large, damaged cylindrical chunk of silver-coloured metal lying in a field at one of the crash sites. Reuters could not immediately verify the authenticity of the image.

‘Act of war’

Islamabad called the assault a “blatant act of war” and said it had informed the U.N. Security Council that Pakistan reserved the right to respond appropriately to Indian aggression. Lt Gen Ahmed Sharif Chaudhry, spokesman for the Pakistan military, said Pakistan would “respond to this aggression at a time, place, and means of our own choice”.

“All of these engagements have been done as a defensive measure,” Chaudhry said. “However, we will take all the steps necessary for defending the honour, integrity and sovereignty of Pakistan, at all cost.”

The South Asian neighbours also exchanged intense shelling and heavy gunfire across much of their de facto border in the Himalayan region of Kashmir, police and witnesses told Reuters.

Hindu-majority India and Islamic Pakistan have fought two of their three wars since independence in 1947 over Muslim-majority Kashmir, which both sides claim in full and control in part.

Since a 2003 ceasefire, to which both countries recommitted in 2021, targeted strikes between the neighbours are extremely rare, especially Indian strikes on Pakistani areas outside Pakistani Kashmir.

But analysts said the risk of escalation is higher than in the recent past due to the severity of India’s attack, which New Delhi called “Operation Sindoor”. Sindoor is the Hindi language word for vermilion, a red powder that Hindu women put on the forehead or parting of their hair as a sign of marriage.

US President Donald Trump called the fighting “a shame” and added, “I hope it ends quickly.” The State Department said Secretary of State Marco Rubio spoke to the national security advisers of both nations, urging “both to keep lines of communication open and avoid escalation.”

U.N. Secretary-General Antonio Guterres called for maximum military restraint from both countries, a spokesperson said. China, which neighbours both India and Pakistan, and Russia also called for restraint.

The shelling across the frontier in Kashmir killed 10 civilians and injured 48 in the Indian part of the region, police there said. At least six people were killed on the Pakistani side, officials there said.

Indian TV channels showed videos of explosions, fire, large plumes of smoke in the night sky and people fleeing in several places in Pakistan and Pakistani Kashmir. Reuters could not independently verify the footage.

In Muzaffarabad, the capital of Pakistani Kashmir, damage from the Indian strike was visible at sunrise. Security forces surrounded a small mosque in a hill-side residential neighbourhood which had been hit, with its minaret collapsed.

A Pakistani military spokesperson told broadcaster Geo that two mosques were among the sites hit by India. The Pakistani defence minister told Geo that all the sites were civilian and not militant camps.

He said India’s claim of targeting “camps of terrorists is false”.

Stock futures, airlines impacted

India’s stock market benchmarks opened lower on news of the strikes.

The benchmark Nifty 50 (.NSEIS) 0.6% lower, but reversed losses to trade 0.1% higher. The Sensex (.BSESN) also rose 0.1%.

The Indian rupee was last quoted at 84.5875 against the US dollar, a 0.2% drop for the day.

Pakistan’s benchmark share index (.KSE) opened down 5.78% but recovered later in the morning, trading down around 1.6% at 0600 GMT.

Several airlines including India’s largest airline, IndiGo (INGL.NS), Air India and Qatar Airways cancelled flights in areas of India and Pakistan due to closures of airports and airspace.

The Indian strike goes far beyond New Delhi’s response to previous attacks in Kashmir blamed on Pakistan. Those include India’s 2019 air strike on Pakistan after 40 Indian paramilitary police were killed in Kashmir and India’s retaliation for the deaths of 18 soldiers in 2016.

“Given the scale of the Indian strike, which was far greater than what we saw in 2019, we can expect a sizable Pakistani response,” said Michael Kugelman, a Washington-based South Asia analyst and writer for the Foreign Policy magazine.

“We’ve had a strike and a counter-strike, and what comes next will be the strongest indication of just how serious a crisis this could become,” he said.