Minor clashes were reported between Congress and BJP-Akali Dal workers in some villages as voting began for the by-election in the Gurdaspur Lok Sabha seat in Punjab on Wednesday.
Election officials said 23-25 percent voting was reported in the constituency. At some polling booths, long queues of voters were seen.
Police said five to six people were injured in clashes between Congress and BJP-Akali activists.
Nearly 15.22 lakh voters, who are eligible to exercise their franchise, will decide the fate of 11 candidates in the fray.
Tight security arrangements are in place. The main fight is between Bharatiya Janata Party (BJP) candidate Swarn Salaria, Congress' Sunil Kumar Jakhar, the Punjab Congress President, and Aam Aadmi Party's retired Major General Suresh Kumar Khajuria.
The by-poll will see a tough fight between the BJP and the ruling Congress.
The Congress, fresh from its emphatic win in assembly elections, is set to give a close contest to the BJP, which is trying to retain the seat.
In the Gurdaspur Lok Sabha constituency, which comprises nine assembly seats, the Congress won seven segments in the assembly polls. One each went to the Akali Dal and BJP.
The AAP, the main opposition party in the Punjab Assembly, could play a spoiler for both the parties. The result will be announced on October 15.
The Lok Sabha seat fell vacant in April following the passing away of veteran actor Vinod Khanna due to cancer. Gurdaspur is the first parliamentary constituency in the country where all polling stations will have Voter Verifiable Paper Audit Trail (VVPAT) machines.
The device gives the voter using an EVM confirmation about the vote.