At least four people were killed and over 300 injured in the violence-struck Banbhoolpura area in Uttarakhand's Haldwani city, Nainital District Magistrate Vandana Singh said.
The deceased were identified as Johny and his son Anas, Aaris and Faheem.
The curfew will remain imposed in Haldwani city till further orders.
After several establishments, including a mosque and a madarsa, which were illegally constructed on government land, were demolished in Banbhoolpura on Thursday, enraged locals pelted stones on police personnel and mediapersons.
Several police personnel sustained injuries in the attack, sources said. The mob also damaged a JCB machine and set 70 vehicles afire, after which authorities imposed a curfew in the area and gave shoot-at-sight order.
Taking note of the violence, Chief Minister Pushkar Singh Dhami convened a high-level meeting over the violence and appealed to the people to maintain peace.