The fire destroyed several documents in the finance and planning office.
The building also houses several National Government offices, including the County Commissioner's office.
Police in Kisumu are investigating the cause of a fire that destroyed a section of county finance offices at Prosperity House on Sunday evening.
The fire destroyed documents in the finance and planning office that also houses directors of budgeting, accounting services, revenue and supply chain management.
The building also houses several National Government offices including the County Commissioner's office, Attorney-General's office and headquarters of the Lake Victoria Basin Commission.
Kisumu County Commissioner Susan Waweru told the Nation Monday morning that police have started investigating the cause of the inferno even as a section of staff said they suspected foul play.
“There was a fire in one of the offices used by the County Government of Kisumu yesterday [Sunday] afternoon which was quickly put out. Police are investigating the cause of the fire," Ms Waweru said.
She added: "Fortunately, the fire did not spread to other offices due to quick action by the fire-fighting department and officers guarding the building.”
Most computers at the IFMIS office were destroyed.
Governor Anyang' Nyong'o and Finance Executive George Omondi remained tight-lipped when contacted over the incident.