Openlands Lakeshore Preserve in suburban Highland Park remains closed after a suspected grenade and other World War II-era materials were found on the lakefront last week.
A device believed to be an old hand grenade was found April 6 on the shoreline near the bottom of a bluff, Highland Park Deputy Police Chief Bill Bonaguidi said in a statement.
On April 9, “other materials” that may have been old War War II aircraft flares were found in the same area, Bonaguidi said.
The origins of the materials are under investigation and criminal activity was not suspected, Bonaguidi said.
The preserve was closed to the public as a precautionary measure while authorities investigate, Bonaguidi said.
Residents who find any unknown materials were advised to leave the area immediately and call 911.