At least 15 dead bodies were recovered from Akaeze River in Ivo Local Government Area on Friday after a commercial bus conveying 38 passengers plunged in the river from the bridge.
Five of the passengers, who were returning from a burial, were rescued and taken to hospital on Friday night.
However, one of them died at the hospital while the others are said to still be unconscious.
Th state governor Dave Umahi has ordered an investigation into the accident.
The governor during his visit to the scene of the accident on Saturday called on all the security agencies to urgently expedite action in unveiling the reason behind the ugly incident.
In a statement signed by the Special Assistant to the Governor on Media and Publicity. Francis Nwaze, the governor also sympathised with the families of the deceased, describing the incident as devastating.
He urged drivers to always exercise caution while plying the routes, noting that the state government is committed to reducing road accidents, hence the increased construction of roads.
The bus, carrying 30 passengers, was recovered from the River as divers from neighbouring States were brought in to rescue the victims.
See video of the moment the bus was lifted from the river.