Media reports said Mumbai police had filed a culpable homicide case against the owner of Ego Media, the company identified as having installed the signage.
Police in the city could not be reached for comment by AFP on Tuesday morning and there was no sign that the owner had been taken into police custody.
City councillor Rakhee Jadhav told AFP that the collapse was avoidable, blaming shoddy construction.
“This is not a disaster. If this hoarding would have been properly installed … these casualties would have not happened,” she said.
“This area is a marshland and it is also a low-lying area,” she added. “The foundation of that hoarding should have gone more near the rock.”