The crash happened around 3 p.m. at Ridge Road and Wildy Road, officials said.
The ambulance was transporting a patient when the crash occurred, the Kendall County Sheriff's Office said.
Five people were taken to hospitals, four from the ambulance and one from another vehicle, officials said. Their injuries were not believed to be life-threatening.
The roadway has been opened as police continue to investigate the cause of the crash.
No further information was immediately available.
This is a breaking news story. Check back for updates.