Mr Thapar was allegedly attacked over his controversial remarks.
Even a policeman accompanying him for security did not deter a group of men from attacking a Punjab Shiv Sena leader with swords in the middle of a busy street in Ludhiana on Friday, allegedly over his controversial remarks against Sikhs.
Two people have been arrested.
A video of the incident shows two 'Nihangs' - members of a warrior Sikh sect who are usually dressed in blue and carry traditional weapons - brutally assaulting the Shiv Sena leader, Sandeep Thapar, while a third keeps the policeman at bay with the help of others.
The leader can be seen riding a scooter with the cop riding pillion when he is accosted by two of the attackers. They have a conversation and Mr Thapar can be seen folding his hands but one of the men starts assaulting him with a sword which appears to be blunt. As the cop tries to intervene, he is taken to the side of the road by a third man.
The first man hits Mr Thapar repeatedly with the weapon on his face and neck as people in vehicles behind him move back. Mr Thapar loses balance and falls to the road with the scooter, when he is attacked by the second man. As he sits on the road with a bloody shirt, the two men ride away with his scooter.
The Shiv Sena leader was taken to a hospital, where his condition is said to be critical.
Police sources said Mr Thapar was returning after attending a trust event around 11.40 am and the 'Nihangs' attacked him because they were angry about his controversial statements against Sikhs.
Ludhiana Deputy Police Commissioner Jaskaran Singh Teja said a case has been registered. Later in the evening, the police said three accused have been identified and two of them have been arrested. The scooter has also been recovered.
Shiromani Akali Dal leader Harsimrat Kaur has attacked the AAP-led government in Punjab and said the incident is indicative of a law-and-order collapse.
Posting a video of the attack on X, Ms Kaur wrote, "Just received a report of an extremely disturbing incident in Ludhiana where a person was attacked with swords despite being accompanied by a security personnel. The manner in which such violent attacks are being conducted in broad day light in busy areas indicates a total collapse in the law and order situation in Punjab. CM @BhagwantMann shud be wake up from his slumber (sic) and take corrective measures immediately."