La Salle County Coroner Rich Ploch announced on Friday that no signs of foul play have been discovered at the explosion site, according to preliminary observations by his office and other law enforcement agencies.
The blast occurred around 7:20 p.m. local time on Thursday, and claimed the lives of three men near Starved Rock State Park.
Furthermore, "it was determined that the individuals appeared to have ignited a type of black powder substance along an area near the riverbank," Ploch stated, as reported by the Associated Press.
Responding law enforcement departments included the Utica Police Department, Illinois State Police, Illinois Department of Natural Resources Conservation Police and the Kane County Bomb Squad.
Utica Fire and EMS are on the scene at the Starved Rock boat ramp in Starved Rock State Park for an explosion that injured three individuals. To life flight helicopter‘s were called but were turned away. No further information is known at this time. pic.twitter.com/se7cOFheoy— Scott Anderson (@NT_Photo2) May 7, 2021
FBI agents were also on the scene and collected a sample of said "black powder substance."
Some have speculated the substance may be gunpowder.
"It’s probably going to be awhile before we find that out unfortunately," Ploch expressed.
The three deceased men have not been publicly identified by authorities.