Rescue crews responded about 9:05 p.m. because the boy was missing and was thought to have been in the pond behind a home in the 6100 block of Haligus Road, according to a statement from the Crystal Lake Fire Rescue Department.
Divers located the boy submerged in about eight feet of water at 10:37 p.m. He was taken in critical condition to Centegra Hospital in Woodstock, the statement said. He was pronounced dead at 11:43 p.m.
Crystal Lake fire crews were assisted by several fire departments from McHenry, Lake and Kane counties. The McHenry County Sheriff's office is investigating.
The Sun-Times Media Wire contributed to this report.