Houston Fire Department investigators say 12 arson fires in west Houston could be related.
The latest fire was at the townhomes on Perthshire near Thicket on Wednesday afternoon.
Houston firefighters said they quickly put it out and kept the damage from spreading beyond three homes.
"We were able to save the son and the dog. That's all that counts, lives count," said Jenifer Smith.
Smith told Local 2 that her son was asleep inside the burning townhome.
"Someone woke him up, told him to get out of the house. It's almost a miracle, not something that you see everyday," said Smith.
A total of 12 fires targeting people in the Dairy Ashford-Memorial area have been set.
The fires were set within the past two months. Firefighters said the arsonists could be three boys or men between 16 and 20-years-old.
Anyone with information on the fires or the people who set them is urged to contact Crime Stoppers. The number is 713-222-TIPS. Tipsters can remain anonymous and could earn a cash reward.