Fire crews and police were called out to an abandoned property on Oldtown Street in Cookstown after reports of smoke coming from the building.
The fire, which started at around 5.20pm on Tuesday evening, is understood to have been set deliberately by someone who broke into the empty property.
Two firemen with breathing apparatus made their way inside, before another crew member climbed on a ladder and tried unsuccessfully to unscrew boarding on a window at the property.
After the building was given the all clear, another fire officer went inside with a sledge hammer and hit out a board on one of the top windows.
The fire was put out at around 6pm.
A Northern Ireland Fire & Rescue Service spokesperson said: “Northern Ireland Fire & Rescue Service [NIFRS] received a call at 5.23pm to a report of a fire at derelict premises at the Oldtown Street, Cookstown area yesterday afternoon [Tuesday 5 May].
“Two Fire Appliances from Cookstown Fire Station were deployed to the scene of a fire on the second floor of a three storey mid terrace building.
“Firefighters wearing breathing apparatus using thermal imaging cameras dealt with the fire.
“The fire was extinguished at 5.54pm and early indications would suggest the fire was started deliberately.
“The incident has now been passed through to the Police Service of Northern Ireland.”