Mr Mbui is said to have suffered the injury as he joined other leaders as well as NASA supporters in marching into the city centre as they received Mr Odinga after his trip to the United States.
Initial reports indicate that the NASA Chief whip fell into a ditch while fleeing from police after his vehicle was smashed. His bodyguard is also reported to have been injured in the incident.
A police statement released on Friday also indicates that five people were killed by stoning during the procession.
"We are aware that sections of the mobs accompanying the NASA convoy, looted property and five persons were killed by stoning in different incidences after having been caught stealing by enraged crowds.Two were stoned along Landies Road, two next to country bus station and one along Racecourse Road.
"Sadly, these incidences occurred before the Police arrived at the various scenes. All these incidences are under investigation," the statement read in part.
Earlier reports had indicated that three people had been shot, however, police maintain that no live bullets were used to contain the crowds.
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Mr Odinga reported that his 10-day trip to the US was a success stating: "Receive greetings from the American people. They are praying for you and have assured me that change in the country is something they will support."
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