The blaze began before 6 p.m. in a private residence above the Legion, but it is unclear how or where the fire started.
"We are investigating the origin of cause ...," said Cartersville Fire Chief Scott Carter. "We know the fire did occur in the apartment, however we don't have the actual origin of cause yet."
Investigators arrived on scene about 6:45 p.m. Sunday to begin the process of determining cause and place of origin.
"Upon arrival we did have fire showing from an apartment that was in the theater complex," Carter said. "We were able to contain the fire to that apartment. There was some water, some smoke damage into the theater, but we were able to keep the fire into the apartment."
Cartersville Fire Department sent three engines, a ladder company and about 12 firefighters to battle the blaze.
The residents were not home at the time. Although firefighters were able to rescue some animals, several animals were deceased, including one cat, Carter said.
The Pumphouse Players are scheduled to present "Tradin' Paint" July 22-31.
Pumphouse President Dave Boggess said at the scene he was unsure how the damage will affect the group and its production.
"We don't know [about the production's future] until we get in and see how extensive [the damage] is," he said.