The Indian Air Force (IAF) is investigating the incident, say sources.
The choppers, which returned to the Chinese side after about five minutes, could have carried out aerial photography of Indian ground troops during what was possibly a reconnaissance mission, said official sources.
The choppers, identified as the Zhiba series of attack helicopters, were seen in the Barahoti region near the border.
In previous incidents, Chinese helicopters had entered 4.5 km into Indian territory, an area that China claims as its own.
State and army officials have been reviewing the security along the 350-km border with Tibet after China's incursions into these areas, generally referred to as the middle sector.
Barahoti on Uttarakhand’s border with China has a long history of incursions by Chinese troops.
In 1958, India and China listed Barahoti, an 80 km square sloping pasture, as a disputed area where neither side would send its troops. In the 1962 India-China war, the Chinese did not enter the 545-km middle sector, focusing on the western (Ladakh) and eastern (Arunachal Pradesh) sectors.
However, after the 1962 war, ITBP jawans patrolled the area with weapons in a non-combative manner, under which the barrel of the gun is positioned downward.
During prolonged negotiations on resolving border disputes, the Indian side had unilaterally decided in June 2000 that the Indo-Tibetan Border Police would not be carrying arms to three posts - Barahoti, Kauril and Shipki in Himachal Pradesh.
Experts call the intrusion of the Chinese choppers an attempt to “test our nerves”.