Deaths were reported on both sides. Pakistan said Indian strikes had killed at least eight people, and India said Pakistani artillery fire had killed three civilians along the de facto border in contested Kashmir.

New Delhi announced it had carried out "precision strikes at terrorist camps" at nine sites in Pakistan-administered Kashmir and in Punjab state, days after it blamed Islamabad for a deadly attack on the Indian-run side of the disputed region.

The Indian army said "justice is served", with New Delhi adding that its actions "have been focused, measured and non-escalatory in nature".

Pakistan's Defense Minister Khawaja Muhammad Asif accused Indian Prime Minister Narendra Modi of launching the strikes to "shore up" his domestic popularity, but said that Islamabad had struck back.

"The retaliation has already started", Asif told AFP. "We won't take long to settle the score."

'Shelling raining down'

Islamabad reported eight civilians -- including one child -- killed in the strikes, and AFP correspondents in Pakistani-run Kashmir and Punjab heard several loud explosions.

In Muzaffarabad, the main city of Pakistan-administered Kashmir, troops cordoned off streets around a mosque Islamabad said was hit by a strike, with marks of explosions visible on the walls of several homes.

Shortly after, India's army accused Pakistan of "indiscriminate" firing across the Line of Control (LoC), the de facto border in Kashmir, with bursts of flame as shells landed, AFP reporters saw.

"Three innocent civilians lost their lives", the Indian army said, adding it was responding in a "proportionate manner".

"We woke up as we heard the sound of firing", Farooq, a man in the Indian town of Poonch, told the Press Trust of India news agency from his hospital bed, his head wrapped in a bandage. "I saw shelling raining down [...] two persons were wounded".

Wreckage of an Indian fighter jet was seen by an AFP photographer at Wuyan – on the Indian controlled side of Kashmir.

A security source confirmed it was an Indian aircraft, but the reason for its crash, and the fate of the pilot, was not immediately known.

India had been widely expected to respond militarily to the April 22 attack on tourists in Indian-administered Kashmir by gunmen it said were from Pakistan-based group Lashkar-e-Taiba, a UN-designated terrorist organization.

That assault left 26 people dead, mainly Hindu men, in the tourist hotspot of Pahalgam. No group has claimed responsibility.

New Delhi has blamed Islamabad for backing the attack, sparking a series of heated threats and diplomatic tit-for-tat measures.

Pakistan rejects the accusations, and the two sides have exchanged nightly gunfire since April 24 along the LoC, according to the Indian army. Pakistan also said it has held two missile tests.

'Maximum restraint'

The violence is a dangerous escalation between the South Asian neighbors, who have fought multiple wars since they were carved out of the sub-continent at the end of British rule in 1947.

Diplomats have piled pressure on leaders to step back from the brink of war. 

"The world cannot afford a military confrontation between India and Pakistan," the spokesman for UN chief Antonio Guterres, Stephane Dujarric, said in a statement, adding that Guterres called for "maximum restraint."

US President Donald Trump told reporters in Washington he hoped that the fighting "ends very quickly".

US Secretary of State Marco Rubio has spoken to top security officials in both New Delhi and Islamabad since the strikes.

Rubio said he was monitoring the situation "closely" and that he would "continue to engage both Indian and Pakistani leadership towards a peaceful resolution".

India's army said it had "demonstrated considerable restraint in selection of targets and method of execution", adding that "no Pakistani military facilities have been targeted".

Pakistani Prime Minister Shehbaz Sharif, calling the Indian attack "unprovoked" and "cowardly", said the "heinous act of aggression will not go unpunished."

Rebels in Indian-administered Kashmir have waged an insurgency since 1989, seeking independence or a merger with Pakistan.

India regularly blames its neighbor for backing armed groups fighting its forces in Kashmir, a charge that Islamabad denies.

Iranian Foreign Minister Abbas Araghchi is expected in New Delhi on Wednesday, two days after a visit to Islamabad, as Tehran seeks to mediate. 

India was also set to hold several civil defense drills Wednesday, while schools in Pakistan's Punjab were closed, local government officials said.

The strikes came just hours after Modi said that water flowing across India's borders would be stopped. Pakistan had warned that tampering with the rivers that flow from India into its territory would be an "act of war".