Kumar told a news agency that the polls were held under strict supervision of a special observer and seven other observers and conducted by 86 polling officials including six nodal officers.
Three platoons of armed policemen were deployed to ensure peaceful polls and maintain law and order in the camps.
He said that the polling, conducted through postal ballots, would continue tomorrow and a high poll turnout was expected.
The 11,612-strong Bru electorate in the relief camps would be exercising franchise through postal ballots in the camps for the Mizoram polls.
The polling party, comprising 74 desk officials and seven nodal officers went to Tripura via Zomuantlang hamlet as the activists of the Mizo Students Union (MSU) organised a blockade at the Mizoram-Tripura border river Langkaih in Kanhmun village on Sunday.
The students objected to the conduct of polling in the camps by sending polling officials from Mizoram as they alleged that the Brus refused to return to the state despite several pleas from the centre, state government and the civil societies.
Chief Election Commissioner VS Sampath, while visiting Mizoram recently said that Bru voters lodged in the Tripura camps were allowed to exercise franchise in the camps in accordance with the Delhi High Court order in 1999.