The billboard collapsed on some houses and a petrol station next to a busy road in the eastern suburb of Ghatkopar following gusty winds and rain late on Monday.
Scores were trapped following the incident with rescue operations continuing till early on Tuesday. The thunderstorm brought traffic to a standstill in parts of the city and disrupted operations at its airport, one of the country's busiest.
Mumbai's municipal corporation said at least 74 people were taken to hospital with injuries following the accident and 31 have been discharged.
Bhavesh Bhinde, the owner of the advertising agency which had allegedly put up the hoarding that crashed on a petrol pump in Ghatkopar area, has 23 criminal cases registered against him and was recently arrested on rape charges, police said on Tuesday evening.
After Monday's hoarding crash in which at least 14 people died, he has been absconding, while a case under IPC section 304 (causing death by negligence) was registered against him at Pantnagar police station in the city.
In January, Bhinde was arrested in a rape case registered with Mulund police station, but later secured bail, a police official said.
Bhinde, owner of Ego Media, had also contested the Maharashtra Assembly elections in 2009, he added.
According to BJP leader Kirit Somaiya, another firm of Bhinde's had been blacklisted by the commercial department of the Indian Railways in 2017-18 after several complaints of installing illegal hoardings were filed against it.
