NORTH UTICA, Ill. (CBS/AP) — Three people were killed Thursday evening when a black powder device exploded in Starved Rock State Park, along a bank of the Illinois River.

Emergency crews were called to a boat ramp at the park around 7:20 p.m. Thursday, and found three dead males, authorities said.

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“With assistance from the (Illinois) State Police, the Kane County Bomb Squad Unit & the FBI, it was determined that the individuals appeared to have ignited a type of black powder substance along an area near the river bank,” LaSalle County Coroner Rich Ploch said.

The three died from injuries they received in the explosion, Ploch said. Autopsies were planned.

The victims’ names have not been released.

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Illinois State Police said they are assisting the Illinois Department of Natural Resources in its investigation of the explosion, along with the FBI, Kane County Bomb Squad, LaSalle County Coroner, Utica Fire Department, and Utica Police Department.

“This is an isolated incident and there is no concern for public safety at this time,” Illinois State Police said in a statement.

Anyone with information on the incident should call ISP at (815) 726-6377.

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(© Copyright 2021 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)

CBS 2 Chicago Staff