India's military says three of its soldiers, including a senior officer, have been killed in a "violent face-off" with Chinese soldiers on the disputed Himalayan border.
China, meanwhile, accused India of crossing the disputed border section.
The June incident, the most serious in many years, occurred late on June 15 in the Galwan Valley in Ladakh where the two sides have been pitched against each other over the past few weeks and skirmishes have been reported.
Military representatives of both sides are meeting to defuse the tension, according to the Indian military statement.
"During the de-escalation process under way in the Galwan Valley, a violent face-off took place yesterday night with casualties. The loss of lives on the Indian side includes an officer and two soldiers," army spokesman Colonel Aman Anand said.
"Senior military officials of the two sides are currently meeting at the venue to defuse the situation," he said.
Chinese Foreign Ministry spokesman Zhao Lijian said Indian troops crossed the border line twice on June 15, "provoking and attacking Chinese personnel, resulting in serious physical confrontation between border forces on the two sides."
The deaths are believed to be the first in decades in the confrontation between the world's two most populous countries. The two nuclear-armed powers have fought one war in 1962, which India lost.
India accuses China of occupying 38,000 square kilometers of its territory. Several rounds of talks over the past 30 years have failed to resolve the boundary disputes.
Based on reporting by dpa, Reuters, AFP, and BBC