LaSalle County, IL – Multiple people are injured after a boat exploded on the Illinois River in the southwest suburbs Saturday, the Illinois Department of Natural Resources said.

Conservation police, as well as state troopers, responded after reports of a boat fire on the Illinois River just before 4:30 p.m. at the Spring Brook Marina in LaSalle County, according to Illinois State Police.

The incident occurred about 4:20 p.m., the IDNR said Sunday. A 40-foot vessel with 17 people on board had just completed fueling. Based on interviews and a review of video footage, authorities said it appears the explosion happened from inside the vessel.

Several families were on the boat, about to get ready to head out on the water when the boat exploded while they were fueling, conservation police said. Thirteen people from the boat were taken to local hospitals to be treated for injuries, the DNR said. One of them was flown to a Chicago hospital with critical injuries. A marine employee also was taken to the hospital for treatment of injuries.

The DNR said information about the identities of the people involved will not yet be released.

The Illinois Conservation Police are leading the investigation with assistance from the Illinois State Police and the Illinois State Fire Marshal’s Office.

The river is open, but boaters are urged to drive cautiously near the site because the sunken vessel has not been removed from the water. The boat is still in the water as officers work to contain the fuel.

Authorities and representatives of the U.S. Environmental Protection Agency are at the scene assisting with recovery operations, which are expected to be completed sometime Sunday afternoon.