The child most likely was between 2 and 3 years old, Frank Shuftan, a spokesman for the Cook County Bureau of Administration said.

They have not been able to determine whether the decomposed body parts found belonged to a boy or girl, police said in a joint news release with the medical examiner's office.

Investigators have DNA, dental evidence, fingerprints and footprints that need to be examined.

"The victim was most likely an African-American child (though mixed race heritage cannot be excluded) between 18 months and 4 years of age (best estimate 2-3 years old)," authorities said.

After a human foot was discovered Saturday in the Garfield Park lagoon, searchers recovered the head, two hands, and another foot of a child, the police department and the city's medical examiner's office have said.

A source with knowledge of the investigation said a citizen made the first discovery in the park.

Chicago police spokesman Anthony Guglielmi said Monday that searchers also found a plastic bag that was brought to a lab to be opened in a sterile environment. Guglielmi said he believes the remains were somehow separated from the bag.

Divers searched the lagoon again Tuesday, the Chicago Police Marine and Helicopter Unit said Tuesday.

After they are done, the lagoon will be drained. It could take 2 to 5 days, CNN affiliate WLS reported.

Parts of the park, which is centrally located near Chicago's New West Side, were still closed Tuesday.

CNN's Greg Botelho and Seth Kovar contributed to this report.