Detective Sergeant Eric Fairfield said: “It was reported to police at around 4.45 am that a property was on fire in the Pretoria Street area of Belfast.
“Police and NIFRS attended the scene.
“NIFRS has deemed this to be deliberate, and so we are treating it as arson at this time.
“This was a reckless act and it’s fortunate no one was injured.
“Enquiries are continuing and we are appealing to anyone who witnessed anything suspicious in the area to contact Detectives in Musgrave on 101, quoting reference number 462 of 23/06/19.
“We are particularly keen to speak to a man believed to have been seen in the area at the time.
“He is described as being in his mid to late 30s, approximately 5’9” with tanned skin, short hair and believed to have been wearing a navy tracksuit.”
Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous and gives people the power to speak up and stop crime.