Joint Chief Election Officer Saibal Barman said the polling was peaceful so far with no incident reported from any assembly segment.
A few EVMs went out of order or malfunctioned at the beginning of the polls and were replaced promptly, he said.
The Election Commission is for the first time using GIS-SMS based poll monitoring system, android-based counting application and live monitoring of sensitive area (LMSA).
The GIS-based poll monitoring system is being used in rural areas to capture images and LMSA for Howrah city, with a video camera on a vehicle being used for the first time.
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Tight security is in place with central forces and state armed police deployed.
"All booths are covered by an armed guard," Chief Electoral Officer Sunil Gupta said adding that general observers Vijay Bahadur Singh and I Anwarudeen, besides an expenditure observer Ranjit Kumar are monitoring the bypoll.
Polling began at 7 am and would end at 6 pm, two hours more than the normal schedule.
The election has been necessitated by the death of Trinamool Congress MP Ambika Banerjee.
Though BJP is not contesting the by-poll, local BJP leader Ranjan Pal is in the fray as an independent.