As well as the fatal victims, the accident also left another Portugese builder in hospital with a fractured leg.
A number of other workers on the building site had to be treated in situ for minor injuries and some of the witnesses to the accident had to receive psychological help.
The concrete sheets fell directly onto the two fatal victims, who were spreading sand below the structure at the time. The worker with the fractured leg was working on top of the structure when it fell.
An investigation into the accident has been launched straight away by the independent Aragon Institute of Health and Safety in the Workplace.
This accident takes the construction site death toll to four so far this year in Aragon and trade unions are calling for a thorough investigation and more measures to prevent accidents of this kind.
Adolfo Barrena of the Izquierda Unida party in Aragon, denounced the incident, saying that yet again people have lost their lives in the course of doing their jobs and called for 'urgent, resolute and decisive measures against accidents in the workplace.
