The incident — the first in decades between the world’s two most populous countries — occurred in the Galwan Valley, in the disputed Aksai Chin-Ladakh area, on Monday night, according to the Indian army.
Ladakh has seen a major troop buildup on both sides of the border in the western Himalayas in recent weeks, before senior military commanders began talks earlier this month.
The Indian army said there had been loss of life “on both sides,” though it did not specify the number of the alleged Chinese casualties.
It said that senior military authorities from the two countries were meeting to deescalate the situation.
China’s Foreign Ministry expressed unawareness of any Indian casualties but said “a serious physical conflict” had taken place on Monday.
During a daily press briefing on Tuesday, Chinese Foreign Ministry spokesman Zhao Lijian said Indian troops “seriously violated our consensus and twice crossed the border line for illegal activities and provoked and attacked Chinese personnel, which led to serious physical conflict between the two sides” on Monday.
The two key Asian countries have rival claims to swathes of territory along their 3,500-kilometer Himalayan border, though their disputes have mostly remained without incident since a 1962 border war between them.
Tensions have been building up along one of the world’s longest land borders since last month, with New Delhi and Beijing both accusing each other of overstepping the Line of Actual Control (LAC) separating the two.