Hundreds of people blocked the road connecting Cakung and Cilincing in North Jakarta, and burned tires during a protest against a planned demolition of their houses on Thursday morning.
Some of the protesters hurled Molotov cocktails at North Jakarta public order officers to prevent them from clearing the slum area.
The incident took place near the KBN industrial estate, Sonora radio reported.
The blockade caused heavy traffic congestion on the opposite lane of the road. Traffic police were also forced to close access to Cilincing from Bekasi in West Java as the congestion worsened.