Mr Femi Adesina, the Presidents Special Adviser on Media and Publicity in a statement in Abuja on Thursday, said Buhari commiserated with the government and people of Anambra State over the sad incident.
He urged hospitals to give the survivors effective medical attention.
President Buhari prayed that the almighty God would grant families of the deceased the fortitude to bear the loss and grant quick recovery to the injured.
The News Agency of Nigeria (NAN) reports that at least seven persons were confirmed dead when a kerosene-laden tanker rammed into traders on the Upper Iweka Road in Onitsha, Anambra, on Wednesday.
The tanker driver was believed to have lost control of the vehicle and knocked down 18 people.