So far there have been three fires - near a middle school, an apartment complex and a church.
"This fire situation is very unsettling and we want to put a stop to it quickly," said Det. John Austin of the Horsham Police Dept.
Investigators were at the Keith Valley Middle School on Wednesday, the site of the first blaze. At about 11:20 p.m. on Saturday, September 18th, someone set a fire inside a dumpster there.
Then, a week later, and at about the same time of night, someone set fire to a laundry basket inside a laundry room at Blair Mill Apartments. However, a smoke detector sounded and a resident found the burning clothes. That person promptly tossed the burning laundry out of the building.
About 90 minutes later, a storage shed at a Montessori center at a church was set on fire.
"I just hope they're able to find him and give him help," said Principal Nona Melnick.
Police are looking for the public's help in finding the arsonist.
"The more the public can help us and the faster we put a stop to this the less people are in danger," said Det. Austin.
You can contact Horsham Police at (215) 643-3600.