Officials confirmed the arrest on Wednesday morning of 33-year-old Frank Milles of Feasterville.
Investigators say Milles is accused of intentionally starting the fire and is charged with arson.
The fire broke out around 7:45 a.m. at the Croftwood Apartments in the buildings located in the 400 block of East Street Road in Feasterville.
Chopper 6 was overhead as firefighters were on the roof looking for hot spots.
Fire at Bucks County apartment complex
Officials said the fire was a one-alarm fire but it proved difficult to put out.
There are no reports of injuries at this time.
The incident remains under investigation.