ORANGE PARK, Fla. -- Clay County authorities report that the body of a small child was found in a landfill near Folkston, Ga., where Orange Park's garbage is dumped.

The Georgia Bureau of Investigation confirmed later Wednesday the body is that of a girl. Investigators said an autopsy will be performed Thursday morning in Savannah, Ga.

A van was seen driving out of the landfill just before midnight Wednesday, escorted by several police cars. It was unclear if it was the medical examiner removing the body because the van was unmarked.

"We hope and pray that it's not the body of Somer (Thompson), but the garbage that was in that area was collected from Orange Park," Beseler said.

Seven-year-old Somer Thompson disappeared while walking home from school Monday afternoon. A massive search of Orange Park has been under way since Monday evening.

Clay County detectives found the body about 3:30 p.m. Wednesday at the Chesser Island Landfill in Charlton County. Sgt. Dan Mahla said the entire landfill has been roped off as a crime scene, and evidence technicians will process the scene as much as possible overnight.

The FBI, GBI and the Charlton County Sheriff's Office are all at the landfill investigating. The Clay County Sheriff's Office is part of that search, but the lead agencies are the FBI and the GBI.

"This was just a hunch -- a standard investigative practice -- and discovered what we feared we were going to find," Beseler said. "Everyone in Clay County, everyone in Florida grieves for this family right now."

Beseler announced the grim news at an afternoon news conference that was delayed for about 20 minutes because of a "major development."

Gov. Charlie Crist was on hand hoping to rally efforts to find Somer and the Justice Coalition was set to announce a $30,000 reward for Somer's safe return.

Instead, that reward will be for information for the capture and conviction of whoever is responsible for putting the body of the child in the trash.

"Everybody's just terribly, terribly sorry and your heart goes to the family," Crist said.

Beseler said Dumpsters in the area are emptied on Tuesdays, and that particular garbage investigators were searching was dropped off Tuesday afternoon.

"Tuesday morning, one of my detectives, Bruce Owens, came forward and said, 'You know, I think it'd be a good idea to follow those garbage trucks and let's look at the garbage on the front end rather than waiting and maybe later on trying to go and uncover something,' which was a stroke of genius," Beseler said. "It was a precautionary thing. We didn't have any idea at that time that this would come about. But it was just a really good move."

State Attorney Angela Corey arrived in Orange Park late Wednesday saying she was there to assist the sheriff and the other law enforcement agencies working on the case.

"It's always a tragedy when we lose a citizen," Corey said. "It is especially so with someone who's a little angel like Somer. It just elevates everything that we do to a new level."

Shelia Clifton, whose 8-year-old daughter, Maddie, was killed by a neighbor in 1998, was at the Orange Park command center on Wednesday trying to do anything she could to help the Thompson family.

"This is so sad that this has happened all over again. It happens way too often," Clifton said. "(Somer's mother) is going to be in shock for a while. She needs all the love and care that everyone can give to her. We need to find the person that did this. That is the most important part right now."

Theresa Neves, the grandmother of missing 6-year-old Satsuma girl Haleigh Cummings, said she was devastated by the news.

"It breaks my heart," Neves said in a phone interview. "I feel so bad for those people. I just pray that God gives that family strength. I don't think there's anything you can say. We hope that God will give (Somer's mother) the strength to get through this."

Sue Rodriguez, the grandmother of Brunswick boy Christopher Barrios, who disappeared and was killed in 2007, reacted to what Somer's family must be going through.

"The biggest thing is turn to your other family, and everybody has to hold on to each other for all the comfort and strength that they can get," Rodriguez said. "People will be praying for them, and prayer will really hold you up real strong."

Clay County school representative Darlene Mahla said grief counselors will be on hand Thursday morning for students and teachers at Grove Park Elementary School, where Somer went to school.

Anna Braddy, whose daughter Kayla is best friends with Somer, said she took Somer to school the day the 7-year-old disappeared. Braddy said it was a normal morning and Somer was her usual self.