While the incidents were not directly related, at least one group of kids was inspired to commit a copycat crime after seeing photos of a previous fire on Instagram, police said.
Fires in two garbage cans at Village Green Park and in a dumpster at Plainfield Central High School marked the third and fourth incident since June 19, Konopek said.
Police apprehended four 16-year-old boys after the incident, which they said started when one of the teens was playing with matches.
"The kid was throwing matches into [the garbage cans] out of curiosity," Konopek said. He said when they were apprehended, the four teens didn't even realize that the garbage cans and dumpster had burst into flames.
The July 10 incident came weeks after the first fire, set June 19 in a dumpster at Walker's Grove Elementary School by a group of 12- and 13-year-olds, Konopek said.
Two days later, a group of kids about the same age pulled a similar stunt, again at Walker's Grove, after seeing photos of the first fire on Instagram, Konopek said.
"Each incident was a different group of kids," Konopek said.
On June 22, another group of youths attempted to start a fire at a playground in the Liberty Grove subdivision, but no damage was done, according to police.
In each incident, the youths were apprehended the same night of the fire, according to Konopek.
Police don't believe the youths are budding firebugs.
"We don't feel that these juveniles are going to continue this behavior," Konopek said, adding that prior to the fires, none of the kids had any police record. "It was a curiosity thing."
Even so, all of them will be required to take a juvenile firesetter program with a local fire department, police said. Each youth will also have to complete community service, and pay restitution for damages where necessary.
According to Konopek, Waste Management, which owns the dumpsters that were set ablaze, has waived any restitution.
Police are working with the Plainfield Park District to determine what will happen as far as replacing the decorative garbage cans at the Village Green. According to park district spokesman Doug Booth, each can cost around $500 to $600 dollars.
Police are urging local parents to be watchful about what their kids are posting online.
"We're asking parents to keep an eye on social media activity," Konopek said.
In a press release, police urged parents who have questions about social media or fire safety to call Sgt. Kevin McQuaid at 815-436-6544 or Plainfield Fire Deputy Chief John Stratton at 815-436-5335.
"The majority of the incidents occurred because the juveniles would post photos on various social media sites after they started the items on fire," police said. " This then caused the other juveniles to commit similar incidents and post them on social media sites ... The Plainfield Police Department would like to remind parents to monitor your children’s social media sites and utilize parental controls when available. Also, talk to your children about the dangers of playing with fire and repercussions that can occur including harming themselves or others."