"We have arrested NCP candidate from Nartiang Umladang Moina K Phyllut and the polling agent last night for his role in the attack at Umladang polling booth," they said.
Phyllut had instigated the mob of around 30-40 men that attacked the booth, destroying the electronic voting machine and assault of two booth officers who sustained back injuries, police said.
The party polling agent's house was torched by angry mob hours later after the attack on the booth, they said.
Following the violence, returning officer and West Jaintia Hills deputy commissioner P S Dkhar has ordered a re-poll in the polling station tomorrow.
Police were also on the look out for at least 10 other persons involved in the incident, who they said have been identified.
Over six lakh tribal voters (6,95,747) cast their votes out of 8,77,615 eligible voters (83.19 per cent) to the two autonomous councils - the Khasi Hills Autonomous District Council and the Jaintia Hills Autonomous District Council - elections held yesterday in which 212 candidates of ten political parties contested for the 58 seats.