The office of the Chief Electoral Officer said that an average of 12.91 percent of voting was recorded in the by-polls to four Assembly seats in Assam till 9 am on Monday.
The officer further informed that Rangapara and Jania Assembly seats recorded the highest voting percent, at 15 percent each in the first two hours of polling, followed by Ratabari at 14.46 percent and Sonari at 7.2 percent.
Voters were seen queuing up at the 830 polling stations across the four constituencies amid tight security.
Some 6,78,898 electors, including 3,27,803 females and one of the third gender, will decide the fate of 20 contestants to the by-polls.
The by-elections were necessitated after BJP MLAs Pallab Lochan Das (Rangapara) and Tapan Gogoi (Sonari), Deputy Speaker of state Assembly Kripanath Mallah (Ratabari) and Congress MLA Abdul Khaleque (Jania) got elected to the Lok Sabha.
The state government has declared Monday as a public holiday, under the Negotiable Instruments (NI) Act, in the four constituencies to facilitate voting.
The results of the by-election will be announced on Thursday, the office of the CEO added.