On Wednesday, which was declared a day of mourning in Khuzestan Province in southern Iran, groups of teary-eyed people gathered in the streets near the site of the 10-story Metropol commercial building to mourn the victims.
Several mourners chanted slogans against Hossein Abdolbaghi, the builder and owner of Metropol.
They rejected official reports that he had been among the victims.
In the wake of the tragedy, Iranian official have made multiple arrests.
Abdolbaghi was initially announced to have been among the detainees, but judicial officials later reported that he had been killed on the spot.
The conflicting reports have led to speculation that he might be alive and allowed to escape.
The unfinished Metropol building, located on Abadan’s busiest street, collapsed on Monday, leaving dozens trapped in the ruins.
A rescue operation is underway to find possible survivors or dead bodies.
Khuzestan’s Deputy Governor Ehsan Abbas Pour told reporters on Thursday that the death toll has reached 18, with two more bodies retrieved.
He said 37 people had also been found alive and sent to hospital for treatment.