The incident came to light today, when a maid servant after getting no response to her knocks at the door, noticed the bodies through a window, following which she alerted the neighbours.
While the parents and three daughters are suspected have ingested poison, the son's body was found hanging, the official said.
"Yesterday, when the maid servant came for work, this person (son) had asked her not to come through the window. He is supposed to have hung himself later in the day, while other deaths are suspected to have happened on Tuesday night itself," Additional Commissioner of Police (Bengaluru) Alok Kumar told reporters here.
"On getting the FSL report we will be able to establish whether the death was due to poisoning or there was any other reason," he added.
Terming the incident "shocking" Kumar said, "All six are from the same family and all of them are adults aged 57, 55, 30, 28, 23 and 27."
According to the neighbours the head of the family was a public sector employee. His son was unemployed and a college drop out, while one of his daughters had recently got engaged.