A utility worker found the body in the outlying middle-class suburb about 9:30 a.m., Orange County Sheriff's spokesman Jim Solomons said. There was nothing that immediately indicated the remains belonged to Caylee Anthony, he said.
CBS station WKMG confirmed that the remains are likely that of a girl. A skull was found nearby, and the body was wrapped in a garbage bag sealed with duct tape, WKMG reports.
Caylee's mother, 22-year-old Casey Anthony, insists that she left the girl with a baby sitter in June, but she didn't report her missing until July. Anthony has been charged within connection with her daughter's death.
Todd Black, the spokesman for Casey Anthony's defense attorney, told the Orlando Sentinel he hoped the discovery was not related to their case.
"If it is, it is a sad day," he said.
Orange County Sheriff's spokesman Angelo Nieves said officials told Caylee's grandparents about the find, but refused to discuss whether the remains were Caylee's.
"It would be premature to speculate," Nieves said. "We're not going to release any more information at this time. We don't want to compromise the investigation."
The FBI and forensic investigators were working at the scene, which sits on the edge of the Anthonys' neighborhood about 10 miles southeast of downtown Orlando.
For the past several months, Anthony's family, police and volunteers from around the country have searched for the little girl.
The child's grandmother first called authorities in July to say she hadn't seen Caylee for a month and her daughter's car. Earlier Thursday, a judge had delayed the mother's trial from January to March.
Earlier this month, the Orange County State Attorney turned over almost 800 pages of documents, which showed someone at the Anthony home had done
In mid-March, someone used the Anthonys' home laptop to search Google and Wikipedia for peroxide, shovels, acetone, alcohol and chloroform. Traces of chloroform, which is used to induce unconsciousness and also a component of human decomposition, were found in the trunk of Casey Anthony's car during forensic testing, the documents say.
Orange County jail officials also released several hours of videotapes of visits between Casey Anthony and her family from July and August, when she was arrested on neglect and other counts but before she was charged with first-degree murder.
During the taped visits, Anthony's parents tell her they're trying hard to find the little girl. Anthony does not appear to add information to aid that search beyond her account that a baby sitter took the girl.
Last week, prosecutors announced they would not pursue the death penalty for Anthony.
The Orange County State Attorney's Office said in a news release last week that "it is not in the best interest of the people of the state of Florida" to pursue the death penalty against Anthony.
Messages left with Caylee Anthony's grandparents and with Casey Anthony's lawyer were not immediately returned.
Leonard Padilla, a bounty hunter who had, at one time, bailed Casey out of jail and searched for Caylee, told WKMG-TV that "it's a bittersweet day."
"We drove by it dozens of times. We heard that there were searches going on in that area," he said."