It is still unclear what caused the explosion at a Nuon power plant in Velsen on Wednesday morning which injured seven, news agency ANP reports.

Police and safety officials were allowed into the complex on Wednesday afternoon in an effort to determine the cause.
Three of the seven injured – not eight as originally thought – were rushed to hospital for treatment. The others were admitted for observation, ANP said.
According to Nuon, the explosion followed by a number of smaller blasts, may have been caused when a high voltage sub-station was closed down ahead of painting work.
The gas-powered generator, which is near a residential area, was not in use at the time of the incident because it is only used when more capacity is needed, ANP said.