The fire broke out at the home in the 1400 block of North Clay Street around 3:43 a.m.
When officers arrived on scene, they found a broken window and a molotov cocktail outside.
There are three apartments in the building, two of which were unoccupied. Eveyone inside the occupied apartment made it out safely.
The second fire was on the porch of a home in the 1100 block of Harvey Street.
The third was a vehicle fire two minutes and two blocks away in the 1000 block of Smith Street.
No one was injured in any of the fires, and the Brown County Arson Task Force is leading the investigation into all three fires.