The incident took place on Janta road in Janakpuri area. Pradeep Chauhan was shot at near Punwarka block by some motorcycle-borne men, SP Prabal Pratap Singh said.
Chauhan was rushed to the district hospital, from where he was referred to a speciality centre.
Members of the Thakur community protested against the incident outside the district hospital.
Earlier in the day, some persons attacked two men while they were sleeping near a brick kiln in Mirzapur village, the police said.
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The police, however, said the incident cannot be linked to the ongoing caste violence.
Meanwhile, a four-member team led by Home Secretary Mani Prasad Mishra and comprising ADG (Law and Order) Aditya Mishra, IG STF Amitabh Yash and DG (Security) Vijay Bhushan arrived here today.
The ADG told PTI that the police are closely monitoring the situation and keeping a tight vigil on inflammatory messages on social media.
Aditya said he met those injured in the violence and recuperating in the district hospital and assured them of the best treatment possible.
The official warned of strict action against those trying to take the law into their hands.
Some unidentified persons had yesterday set fire to at least 12 houses of Thakurs in Shabbirpur village ahead of the arrival of Bahujan Samaj Party (BSP) chief Mayawati there.
A mob later attacked a group of people returning from a rally of Mayawati, killing Ashish (24), who hailed from Sarsawa town, on the spot and injuring four others.
The Uttar Pradesh government has announced Rs 15 lakh as compensation to the family of the man and Rs 50,000 each to those injured.