More than 15 fires have been intentionally set in the last five months and all were believed to be related, according to Fullerton police Sgt. Jon Radus.
"Our concern is that these fires will become more than just property damage at some point and will risk lives," Radus said.
Officers have stepped up patrols in the area of the 1200 block of North Gilbert Street and were asking the public to keep an eye out.
If you have any information that could aid detectives in their investigation, you were urged to call Fullerton Police Department Property Crimes Sgt. K. Hamel at (714)738-5336.
Watch Greg Lee's full report in the video player above.