Toyota has extended its production shutdown to 10 vehicle assembly lines at six plants in Japan due to component shortages following an explosion at a key supplier.

The automaker has 14 assembly plantsin Japan producing vehicles for domestic and export sale.

The automaker said it was having difficulties procuring springs for suspension systems and other applications for several models, including the RAV4 and Landcruiser SUVs, following an explosion at a factory owned by Chuo Spring in which two of workers were said to have been injured. The cause of the accident, which happened in the plant’s steel cooling section, was being investigated.

Toyota said it had closed 10 production lines by Tuesday with others plants also likely to be affected and the automaker unable to say when production would resume as it scrambles to find alternative component supplies.

Single sourcing of components and just in time production, while cost effective and efficient, has compounded this as the automaker was carrying minimal stock.