There were around 40 flats in the building, the official said, adding those rescued were shifted to a local hospital at Mahad, which is around 170 km from Mumbai.
The incident took place near Khalapur, over 60 km from Mumbai, when the Tata Safari car in which they were traveling to Pune rammed into a truck.
The police, fire brigade, teams of the National Disaster Response Force and local trekkers were making efforts to pull out all bodies from the accident spot, a senior police official said.
The bus was carrying 34 staff members of an agriculture university in the Konkan region. It fell into a 500-feet deep gorge at Ambenali Ghat near Poladpur town, District Collector Vijay Suryawanshi said.
The five-storey building -- Tareq Garden -- in Mahad town, around 170 km from Mumbai, collapsed on Monday evening. According to a police official, the rescue operation was called off around 11.30 am on Wednesday.
The two western states, already battling a raging pandemic, which has put their health infrastructure under severe strain, opened new fronts to tackle the fallout of the storm which is expected to make a landfall close to Mumbai on Wednesday. They are likely to be impacted most by the cyclone.
With the cyclone set to make landfall on Wednesday, Maharashtra and Gujarat activated their disaster response mechanism, deploying NDRF teams and evacuating people from areas likely to be hit.