No one was injured in any of the brush fires that began last December at Artesian Fields, a passive park with walking and running trails, said Police Chief Michael Foligno, who is also the borough administrator.
The most recent was mid-Friday morning.
Elmwood Park firefighters doused them all relatively quickly, Foligno said.
Foligno's detectives are investigating with their colleagues from the Bergen County Prosecutor's Arson Investigations Unit.
The Bergen County Sheriff's Office has supplied K-9s to help investigate and its Bureau of Criminal Identification to collect evidence.
Anyone who might have seen something or has information that can help authorities identify those responsible for the fires is asked to call Elmwood Park police: (201) 796-0700.
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