According to Chinese news outlet CCTV, the fire started near the Jokhang Temple in Lhasa at 6 pm local time. The incident occurred during the Losar festival, which celebrates the first day of the lunisolar Tibetan calendar.
No casualties have been reported so far and local authorities said that the relics remained intact.
It is still unknown what triggered the incident.
Founded in 652, the temple has been enlarged several times and is considered one of the holiest sites for Buddhists.
The social media users are uploading the images and the videos allegedly showing the temple's roof in flames.