The unidentified remains of victims killed during the Sept. 11, 2001 terrorist attack on the World Trade Center were returned to Ground Zero is a quiet ceremony.

The remains will be kept in a repository at the National September 11 Memorial & Museum, where New York City's chief medical examiner's office will continue trying to sort through the nearly 8,000 fragmented remains to victims not yet identified, reports Reuters. Though the remains will be on site, only the medical examiner, their staff and victims' family members will be able to enter the repository.

They were moved Saturday morning in a quiet procession that featured fire, police and Port Authority vehicles. They flashed their lights, but kept sirens off during the journey to Ground Zero from the Manhattan forensics lab.

Not everyone is happy with the decision to keep the unidentified remains at Ground Zero, according to The Associated Press. Some families silently protested the move by wearing black bands covering their mouths while watching the procession reach Ground Zero.

They feel the repository feels like it is part of the museum and the remains should instead be kept at an above-ground monument.