The Shorewood police warned residents to stay off any chunks of river ice because they are unstable and may cause injury.
Residents were sent away from the banks of the DuPage River in Shorewood where they were climbing on the large chunks of river ice, Shorewood police said in a news release.
Ice chunks may weigh up to 700 pounds and are unstable as they continue to melt, police said.
“You could be injured if they shift and you may fall into the river. For your safety, stay away and keep children away,” police said.
Shorewood Police Chief Aaron Klima said the ice chunks are not like ice cubes and can be half the size of a car. He said there are “literally dozens of these things all over the place.”
He said on Monday he saw two teenagers rocking on an ice chunk as if it were a seesaw. He said the teenagers could have fallen into the river and become seriously injured.
“The are unstable, they’re going to melt. … They’re huge. Some of them weigh hundreds of pounds,” Klima said.
Ice jams are caused by melting snow and ice in the springtime, according to the National Oceanic and Atmospheric Administration’s website. Warm temperatures and spring rains cause snow and ice to melt very rapidly.
The extra water causes frozen rivers and streams to swell up, and the layer of ice on top of the river begins to break up, according to NOAA.
The river carries large chunks of ice downstream and ice chunks can get stuck.