July 4 (UPI) — Three children were killed Friday when a severe storm capsized a boat in Wisconsin, police said.

The privately owned, recreational motorboat had six adults and four children aboard on Geneva Lake, and all children were wearing life jackets.

When a storm hit, the boaters tried to find their way to safety but were overwhelmed by high winds and waves. The boat capsized and later sank.

Rescuers were able to quickly help the adults and one child out of the water, but three were still missing. After an intensive search, they found all three. Rescuers took lifesaving measures on the scene and on the way to a hospital, but all three children were pronounced dead.

“Our hearts and prayers go out to the families of those, not only of those people, but the people who were injured as a result of the storm. We know that there were many injuries, people transported to local hospitals and diversion from the hospitals because of the number of injuries,” Walworth County, Wisc., Undersheriff Tom Hausner said.

The storm hit at about 12:10 p.m., and 911 calls began coming in around the same time, Hausner said.

A source told CBS News Chicago that the three victims are believed to be younger than 13.

The deaths are under investigation by the Geneva Lake Law Enforcement Agency and the Wisconsin Department of Natural Resources.

A squall line of storms moved into northern Illinois and southern Wisconsin Friday morning and early afternoon, with wind gusts of up to 60 mph, The New York Times reported. Nearly 514,000 homes and businesses in Michigan, Illinois and Wisconsin were without power Friday night.