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 neighbours.

The Indian strikes included targets in Punjab, its first attacks on Pakistan's most populous province since the last full-scale war between the old enemies more than half a century ago, triggering fears of further hostilities in one of the world's most dangerous flashpoints.

Pakistan said India "had ignited an inferno in the region" and that it would respond "at a time, place and manner of its choosing to avenge the loss of innocent Pakistani lives and blatant violation of its sovereignty".

India said it struck nine "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. Four of the sites were in Punjab and five in Pakistani Kashmir, it said.

India had earlier said two of three suspects in the tourist attack were Pakistani nationals but has 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 wounded, a Pakistan military spokesperson said.

Indian forces attacked facilities linked to Islamist militant groups Jaish-e-Mohammed and Lashkar-e-Taiba, two Indian military spokespeople 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 spokespeople said.

They said Indian forces 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.

A statement from the Pakistan prime minister's office said five Indian aircraft and drones had been shot down, a statement not confirmed by India.

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.

'OPERATION SINDOOR'

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.

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

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.

U.S. 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".

Nationalism and anger against the other prevailed among many people in both countries.

"Pakistan has been testing our patience. The good thing is India is taking revenge," said Kumar Ravi Shankar, a Delhi lawyer.

"The precision strikes are a strong and appropriate response. The focus should remain on eliminating terrorism at its roots," added Tejas Patel, 42, a finance professional in Prime Minister Narendra Modi's home state of Gujarat.

In Pakistan, businessman Umbreen Mahar said: "No one in today’s world wants to favour war. But if India continues to slander us and then attack, Pakistan has the right to retaliate and defend its sovereignty."

Analysts said the risk of escalation was 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.

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.

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 an 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.

STOCK FUTURES, AIRLINES IMPACTED

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

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

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

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

Several airlines including India's largest, IndiGo (INGL.NS), opens new tab, 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 airstrike 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 counterstrike, and what comes next will be the strongest indication of just how serious a crisis this could become," he said.