A nationwide search is under way for a missing Illinois boy after his mother left behind a suicide note saying the child was in the care of unspecified people, Fox 8 reports.

Six-year-old Timmothy Pitzen, of Aurora, Ill., was last seen over a week ago when he and his mother left for a road trip to the Kalahari Resort in Wisconsin Dells, Wisc. 

Authorities say the boy's mother, 43-year-old Amy Fry-Pitzen, committed suicide at a hotel in Rockford, Ill., on Saturday. 

Fry-Pitzen reportedly left behind a note, saying Timmothy is "okay" and with people who care about him but did not name the individuals.  

"We believe he's alive. We believe that she told someone to watch him and that she would be back," the boy's grandmother told Fox 8. 

The FBI and U.S. Marshals service are now assisting the Aurora Police Department in the hunt for the boy, according to the station. 

Timmothy, described as 4-foot-2 and weighing 70 pounds, lived with his mother and father, Jim Pitzen, in Aurora.

His father said in an interview with Fox 8 that he doesn't understand why his wife killed herself. 

"I don't know why my wife did what she did," Pitzen said. "I don't know where my son is. It's just terrifying for me to know he is there with somebody I don't know."

The boy, who has brown hair and brown eyes, was last seen wearing green shorts and a Spider-Man backpack.

Anyone with information on his whereabouts is being urged to call the Aurora Police Department at (630) 256-5500.

Click here for more on the disappearance of Timmothy Pitzen from Fox8.com