Three people have been reported to have been injured on Monday afternoon after fire broke out at the 20th Century building along Mama Ngina Street in Nairobi's CBD.
Among the injured was a pregnant woman, who was rushed to hospital in an ambulance.
According to John Opinde, a security officer who witnessed the incident, those who were injured were trying to escape the smoke which had engulfed the building.
"It started on the ground floor, we saw some smoke then within minutes we heard a loud sound like lighting before the fire started spreading," said Mr Opinde.
He added that the fire would have been contained faster, but the cars parked outside the building had to be removed first to create room for fire engines to access the building.
Opinde said that most of the people inside the building managed to escape because most of the offices in the building are not fully occupied.