Residents of Wilmington were warned of “life-threatening” flooding as the Kankakee River rose to dangerous levels in Will and Grundy counties Friday morning.

The National Weather Service urged people in Wilmington to move to higher ground because of flash flooding that could occur in parts of the town.

An ice jam has formed on the river from the extreme cold last week, according to weather service meteorologist Kevin Doom. When the ice jam breaks, flooding could happen quickly and without warning.

“That’s just something we’ll have to keep an eye on,” Doom said. “Once that happens, that’s the potential for some rather rapid onset flooding.”

After rising around 3 feet in the course of an hour, the Kankakee River was recorded at 4.32 feet around 5:45 a.m. Friday. The flood level is considered 5 feet, according to the weather service.

Residents of downtown Wilmington should be prepared to take action, including evacuating, the Will County Emergency Management Agency said in a post on X.

“Life-threatening flash flooding is occurring in the vicinity of downtown Wilmington,” the post read.

The North and South Islands near Wilmington in the Kankakee River have been evacuated, according to Will County Emergency Management.

Illinois Route 53 was closed between 1st Street and Illinois Route 102/Water Street as of 7 a.m. Friday.

A flash flood warning is in effect until 9:15 a.m. Saturday, but that could be extended depending on when the ice jam breaks, Doom said.