Blasts rang out across the city of Jammu in Indian Kashmir late on Thursday during what Indian military sources said they suspected was a Pakistani drone attack on the second day of clashes between the two neighbours.
Several parts of Jammu and the surrounding towns of Akhnoor, Samba and Kathua came under attack, according to Indian officials.
There was no immediate comment from Pakistan on what appeared to be an escalation in the countries' worst confrontation in more than two decades.
Pakistan’s Defence Minister, Khawaja Muhammad Asif, had earlier said further retaliation was “increasingly certain” after both countries accused each other of launching drone attacks.
India said it hit nine "terrorist infrastructure" sites in Pakistan on Wednesday in retaliation for what it says was a deadly Pakistan-backed attack in Jammu and Kashmir on April 22.
Pakistan says it was not involved and denied that any of the sites hit by India were militant bases. It said it shot down five Indian aircraft on Wednesday, a report the Indian embassy in Beijing dismissed as "misinformation".
Pakistan said earlier on Thursday it shot down 25 drones from India overnight, while India said its air defences had stopped Pakistani drone and missile attacks on military targets.
World powers from the US to Russia and China have called for calm.
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