The injured were rescued and shifted to a private hospital where one of them is in a critical situation.
Many are feared to be trapped in the collapse.
Locals also helped in the rescue operations.
This content is restricted to site members. The building was located on Kasavanahalli on Central Jail Road near Haralur.
"They had constructed five storeys in the building, but only three were sanctioned", Mayor Sampath Raj was reported as saying.
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The State Disaster Response Force was pressed into the rescue operations, along with the police personnel. The owner of the building is identified as Ahmed, a Kerala based man. The people who were nearby started rescuing the labourers, while informing the rescue team.
The building was under construction for over six years and was abandoned after the construction stopped two years ago.
All the people trapped inside are construction workers, Raj said. Just last week, two buildings - one in Yeshwanthpur and another in Jayanagar - had dangerously tilted to one side. That time, it was the building of extra floors than the approved plan which caused the mishap.
At least three people died and seven others were injured after a five-storey under-construction building collapsed on Thursday in Kasavanahalli in Bengaluru.