Several investigations have now begun into the overnight explosion and fire at a Shell chemicals plant in Moerdijk near Rotterdam.

Moerdijk mayor Jac Klijs told a news conference on Wednesday afternoon several probes are now underway, including one involving the public prosecution department.

Shell says it has no idea what caused the explosion, at around 22.45 on Tuesday evening. ‘We don’t even have the beginings of an idea,’ location head Paul Buijsingh told reporters.

He said the company regretted that locals were so worried about the impact of the fire. ‘Fires like yesterday’s are extremely rare,’ he said. ‘But in this industry, we can never say there is zero risk.’

Klijs confirmed that the chemical ethyl-benzene had been released during the blaze but said it is not cancer causing. Soot samples taken at various locations are now being analysed as well, he said.