An Indian Army Colonel and two soldiers have been killed in clashes with China.
Senior military officials from both sides have been scrambled to the border as fears grow of a military escalation.
China for its part has accused Indian troops of carrying out “provocative attacks” leading to “serious physical conflicts” in a disputed border area.
The standoff took place in the Galwan Valley in Eastern Ladakh.
Chinese state media has reported five soldiers were killed and 11 were injured at the China-India border on Monday.
The Chinese Foreign Ministry was quoted as saying both sides had “agreed to resolve the bilateral issues through dialogue to ease the border situation and maintain peace and tranquillity in border areas”.
In a statement, the Indian Army said: “A violent face-off took place last night with casualties.
“The loss of lives on the Indian side includes an officer and two soldiers.”
Army officials also said senior military chiefs from both sides are currently meeting at the site of the shooting to try and defuse the situation.
Beijing has accused India of crossing the border and “attacking Chinese personnel”.
The country’s Foreign Ministry said it called on India not to stir up trouble or take unilateral actions.
There has been an upsurge in tensions between the two superpowers in recent weeks.
The last time shots were fired on the border was in 1975.