"The turnout so far is good. In the first two hours, polling was 21 per cent," officials said.
An electorate of 1.26 crore will decide the fate of 366 candidates, including several ministers, in 15,711 polling stations.
The constituencies going to polls during this phase include Nandigram and Singur which changed the political scene in the state in the last few years.
Besides CPI(M) heavyweight and Industries Minister Nirupam Sen, other CPI(M) ministers in the fray include Higher Education Minister Sudarshan Roychowdhury, Food Processing Minister Mohanta Chatterjee, Minister of state for Information and Culture Soumendranath Bera and Technical Education Minister Chakradhar Maikap.
Agriculture Minister Naren Dey belonging to Forward Bloc and Fire Services Minister Pratim Chatterjee belonging to Marxist Forward Bloc are also contesting.
Trinamool Congress has fielded former IPS officers Rachpal Singh, H A Sawfi and Sultan Singh in this phase.
The six-phase election will end on May 10.