Mr Masters said the owner went to investigate when the smoke alarm sounded at 2.30pm and discovered a toilet roll holder in one of the men's cubicles was on fire. She evacuated her customers and ran to the kitchen to get a fire extinguisher.
"She was about to head into the fire when a good Samaritan grabbed the extinguisher off her, saying 'that's my job', and put out the fire."
Firefighters and police arrived quickly and spoke to a 9-year-old boy, who has been referred to police Youth Aid. CYF is also assisting.
Police were confident the boy was responsible for both blazes. The boy's caregiver, who was oblivious to his actions, was shocked and cooperative, Mr Masters said.
Cafe owner Marian Ralph said it was an off-duty fireman, who had stopped in for a coffee, who intervened and put the blaze out.