On Friday, in the largest of the seven phases, 166 million voters in 102 constituencies across 21 states and territories will vote
Television channels said nearly 100 people may be trapped in the building that houses the office of state-owned telecoms company MTNL.
"The fire has been confined to the third and fourth floor of the building," the fire department, which has dispatched 14 fire engines to the site, said in a text message.
A Reuters witness said five or six people were on a balcony on one floor, with some waving white handkerchiefs.