Several others are feared trapped, police said.
The injured have been shifted to a nearby hospital while rescue operations have been taken up on a war-footing.
The condition of one of the injured is said to be critical.
Police said the under construction building at Kasavanahalli suddenly collapsed about 3.30 pm, trapping many.
Fire brigade and police personnel, who were informed, launched rescue operations assisted by local people.
Also Read
Two labourers were found dead under the debris while one of the rescued succumbed to injuries in hospital, Bengaluru Mayor R Sampath Raj said.
"We are gathering more information.It was developed to accommodate paying guests but later the owner tried to convert it into a commercial building," he said.
The construction had started six years ago but was stopped midway. Six months ago, the construction began, the deputy commissioner said.
It is learnt that there were labourers from other states as well.
Raj said the building collapsed because of weak foundation.
"Rescue team is at work.... the rescuers have gone inside the building," he said.
Disclaimer: No Business Standard Journalist was involved in creation of this content