At least four people were killed and 15 others injured after a matatu lost control and overturned along Enterprise Road in Nairobi on Wednesday night.
There are fears the toll will increase as many of the injured were serious.
The matatu belonged to Risen Sacco, police said.
According to police, the fatal crash occurred at about 8:00 p.m. on June 3, near the Dar es Salaam Roundabout opposite KCB Bank within the Industrial Area.
Police said the vehicle was heading from the DT Dobie direction towards General Motors when an unidentified motorcycle allegedly emerged from Dakar Road and failed to give way.
In an attempt to avoid colliding with the motorcycle, the driver swerved, struck the central island kerb at the roundabout, lost control of the vehicle and overturned onto its left side.
The motorcycle rider fled the scene immediately after the incident.
The driver sustained a fractured left leg and was rushed to hospital for treatment.
Four victims died at the scene after sustaining multiple injuries. They included three passengers and an unidentified female pedestrian believed to be about 30 years old.
Fifteen other passengers aboard the minibus suffered various injuries and were taken to different hospitals for treatment.
Police officers visited the scene and launched investigations into the crash. The bodies of the deceased were moved to the Nairobi City Mortuary pending identification and post-mortem examinations.
Authorities are also seeking to trace the motorcycle rider who allegedly triggered the chain of events leading to the deadly accident.
But some passengers onboard said the driver was moving at high speed and recklessly. Police have in the past days complained that some drivers are reckless and invoke names of politicians to flout traffic rules. This has become hard to enforce the law.
The accident increased to 11, the number of people killed in separate accidents in the country on Wednesday night.
They included five pedestrians, four passengers, a rider and a pillion passenger.
Police said 25 other people were seriously injured in the accidents and included three pedestrians, three drivers and 16 passengers.
There is a campaign to address accidents in the country.
