Officials said that four persons were trapped in the debris after the slab collapsed and brought down with it the common passage of the first, second, third and the fourth floors of the building.
"Three workers who were brought out from the debris were declared dead by hospital authorities. One person is still missing," Dyaneshwar Chavan, Deputy Police Commissioner of Zone 2 told PTI this evening.
A search and rescue operation for another worker is on, said an official from the disaster management cell of the Brihanmumbai Municipal Corporation (BMC).
Fire brigade officials said the labourers were working on the first and fourth floor. The building was undergoing repair when the collapse occurred, they said.
Fire Brigade chief PS Rahangdale said that narrow lanes and congestion was hampering the work of fire brigade personnel at the site.
Zaveri Bazar is the centre of the city's bullion market and sees heavy traffic and pedestrian footfalls every day.