Artillery fire and attack drones were witnessed in Jammu and Kashmir, the centre of much of the fighting, while blasts from air-defence systems boomed in cities under blackout, similar to the previous evening, according to authorities, residents and Reuters witnesses.
Indian Foreign Secretary Vikram Misri told reporters Pakistan had violated the understanding arrived at by the two countries earlier on Saturday, and the Indian armed forces had been instructed to "deal strongly" with any repetition.
"We call upon Pakistan to take appropriate steps to address these violations and deal with the situation with seriousness and responsibility," Misri told a media briefing.
In response, the foreign ministry of Pakistan said the country was committed to the ceasefire and blamed India for the violations. "Our forces are handling the situation with responsibility and restraint," it said.
The ministry also called on troops on the ground to exercise restraint and said any issues in the implementation of the ceasefire should be addressed through communication at appropriate levels.
"Pakistan and India have agreed to a ceasefire with immediate effect," Foreign Minister Ishaq Dar posted on social media platform X.
"Pakistan has always strived for peace and security in the region, without compromising on its sovereignty and territorial integrity!"
Misri had earlier said the chiefs of the two countries' military operations had spoken to each other and agreed that all fighting would stop at 5pm Indian time (9.30pm AEST) on Saturday.
US President Donald Trump posted news of the ceasefire on his Truth Social account.
"After a long night of talks mediated by the United States, I am pleased to announce that India and Pakistan have agreed to a FULL AND IMMEDIATE CEASEFIRE. Congratulations to both Countries on using Common Sense and Great Intelligence."
Dar told the broadcaster Geo News that military channels and hotlines between India and Pakistan had been activated, and three dozen countries had helped to facilitate the agreement.
On Wednesday, India had attacked what it said was "terrorist infrastructure" in Pakistani Kashmir and Pakistan, two weeks after 26 people were killed in an attack on Hindu tourists in Indian Kashmir.
Pakistan denied India's accusations that it was involved in the attack. Days of cross-border fire, shelling and drone and missile attacks followed, with the combined civilian death toll at 66.
US Secretary of State Marco Rubio said he and Vice President JD Vance had engaged with Indian Prime Minister Narendra Modi and Pakistan's Shehbaz Sharif, Indian Foreign Minister Subrahmanyam Jaishankar, Pakistan's army chief Asim Munir, and the two national security advisers over the course of 48 hours.
News of the ceasefire was greeted with relief on both sides of the border and Pakistan's airport authority said its airspace had been fully reopened.
But the subsequent violations sparked alarm in India.
"What the hell just happened to the ceasefire? Explosions heard across Srinagar!!!", Omar Abdullah, chief minister of Indian Kashmir, posted on X.
"This is no ceasefire. The air defence units in the middle of Srinagar just opened up."
