What was the cause of the fire accident in Shushtar Refinery?

According to Energy Press, Mohsen Paknejad told reporters on the sidelines of the meeting of the government delegation: In today’s meeting of the delegation of ministers, general issues related to the budget and financial relations of the National Oil Company with the government were raised. The supporting role of the president and other members in relation to the oil issue remained.
Referring to the Shushtar accident, he said: A non-governmental refinery in Shushtar industrial town with an operating license from the Ministry of Security had an accident. What happened in this refinery was probably caused by the negligence of the tanker driver. The driver should have followed the rules while loading, which he did not, although the accident was quickly contained. I do not have the latest statistics on the number of casualties and damages.