Four more persons have died from the accident involving two vehicles on the Lagos-Ibadan expressway on Wednesday.
The Federal Road Safety Corps (FRSC) in Ogun said the death toll has increased to 13, from nine announced earlier.
The Sector Commander of the FRSC in the state, Mr Ahmed Umar, told newsmen on Thursday, in Ota, that the four died on their way to the hospital.
The injured are now 12, he said.
FRSC Sector Commander said on Wednesday that nine people died while 16 others sustained various degrees of injuries in the ghastly accident.
He explained that the accident occurred at about 3.45 pm around Wichtech Company, near Danco Station, on the ever-busy expressway.
He said that the accident involved a commercial white Mazda bus, with registration number: APP 28 YE, and a blue Volvo truck, with no registration number.
The sector commander further stated that the accident involved 25 persons, indicating that the corpses of the deceased have been deposited at the morgue of Idera Hospital, Sagamu.
He said the injured are receiving treatment at the same hospital.
Umar said that the cause of the accident could be traced to speed violation and overloading on the part of the commercial bus driver.
He added that the driver of the commercial bus lost control due to excessive speeding and rammed into the truck.
The sector commander said that clearing of obstruction caused by the crash by FRSC officials and other sister agencies has commenced.
He advised motorists to exercise patience and remain calm, as the situation in the axis would soon be normalised.