Hundreds of residents took to the streets of Abadan, the capital of the southwestern Iranian province of Khuzestan, late on May 25, chanting slogans against the Iranian authorities.
The protest came following the May 23 collapse of an unfinished building in Abadan that killed at least 19 people and injured nearly 40, according to official figures.
Rescuers are still searching for dozens of people who are believed to be trapped beneath the collapsed building.
An emergency official interviewed earlier this week on state television suggested that some 50 people may have been inside the building at the time of the collapse. However, it wasn't clear if that figure included those already pulled from the rubble.
Many in the city are angered by the incident, blaming city officials for the deadly accident.
An angry crowd at the site chased and beat Abadan Mayor Hossein Hamidpour immediately after the collapse, according to the semiofficial ILNA news agency and online videos.
Critics say the building work was poorly constructed due to efforts to save on costs.
Videos posted online on May 25 showed crowds mourning those killed while beating their chests.
Some chanted that the 1979 revolution was a mistake, while others said, “Death to incompetent authorities.”
The head of Khuzestan Province's judiciary has ordered a probe into the accident.
Iranian President Ebrahim Raisi has offered his condolences and appealed to local authorities to investigate the case. Iran’s vice president in charge of economic affairs, Mohsen Rezaei, and Interior Minister Ahmad Vahidi visited the site.