Local people gathered near the river since morning suddenly turned restive and set fire to a JCB machine, a generator set and other equipment at the construction site, Sub-Divisional Officer (SDO) Kari Mahto said.
A protester was injured after the JCB machine exploded, he said.
The protesters also blocked a passenger train.
The SDO, who is camping on the spot with the Deputy Superintendent of Police (DSP) Jairam Sharma since yesterday, said that a 15-member NDRF team was removing hyacinth plants in the river to locate the bodies of the four labourers who fell into it after the bridge collapsed yesterday.
