Eskom has launched an investigation into an accident involving 13 workers at the site of the Ingula hydropower project. The South African utility says that six construction employees were killed and a further seven injured when a gantry failed and collided with other infrastructure at the site in KwaZulu-Natal province on October 31st.

Work at the project site, where Eskom is building a 1332 MW pumped storage facility, ceased and the company says it is reviewing safety standards at all construction projects.

According to a statement from Eskom, the incident occurred at around 8:15-9 am in the construction site’s units 3 and 4 incline high pressure shaft. A wheel-based gantry started moving down an incline and collided with a monorail and two other gantries, which then hit the workers.

Of the seven injured workers, four were treated and discharged from hospital while three remain in intensive care, according to local reports dated November 6. The rescue operation entailed the use of sniffer dogs, helicopters and paramedics.

Ingula is due to start operating at the end of 2013 and is expected to cost a total of R25 billion. Some 3387 workers are building the project.

"With thousands of workers on our power-plant construction sites at Medupi, Kusile and Ingula, this incident clearly requires a renewed focus on safety so that we do not only bring new generating capacity online for the country, but that we do so safely," stated Eskom Chairman Zola Tsotsi.

Eskom CEO said that the company is "determined to find out why it happened and how to safeguard against it happening again".