Rescuers are digging through the debris of a building collapse in south-western Iran that killed at least 11 people, fearful that many more could still be trapped beneath the rubble.

Elsewhere, authorities arrested the city’s mayor in a widening probe into the disaster.

The collapse on Monday of an under-construction 10-storey tower at the Metropol Building exposed its cement blocks and steel beams while also underscoring an ongoing crisis in Iranian construction projects that has seen other disasters in this earthquake-prone nation.

Video from the initial collapse showed thick dust rise over Abadan, a crucial oil-producing city in Khuzestan province, near Iran’s border with Iraq.

The Metropol Building included two towers, one already built and the other under construction, though its bottom commercial floors had finished and already had tenants.

On Tuesday, an emergency official interviewed on state television suggested that some 50 people may have been inside of the building, including people moving into its basement floors.

However, it wasn’t clear if that figure included those already pulled from the rubble.

At least 39 people were injured, most of them lightly, officials earlier said.

Aerial drone footage aired showed the floors had pancaked on top of each other, leaving a pile of dusty, grey debris.

A construction crane stood still nearby as a single backhoe dug. State TV said at least 11 people had been killed.

An angry crowd at the site chased and beat Abadan Mayor Hossein Hamidpour immediately after the collapse, according to the semi-official ILNA news agency and online videos.

Police later arrested Hamidpour and nine others, Iranian media reported on Tuesday.

Initially, authorities said the building’s owner and its general contractor had been arrested as well, though a later report from the judiciary’s Mizan news agency said the two men had been killed in the collapse.

The conflicting reports could not be immediately reconciled.

Authorities offered no immediate word on whether those detained faced charges and it wasn’t immediately clear if lawyers represented them.

Iranian President Ebrahim Raisi offered his condolences and appealed on the local authorities to get to the bottom of the case.

Iran’s vice president in charge of economic affairs, Mohsen Razaei, and Interior Minister Ahmad Vahidi visited the site.

-AP