The unidentified remains of those killed at the World Trade Center are returning to the World Trade Center site.

The remains are being moved at dawn Saturday from the Chief Medical Examiner's office on Manhattan's East Side. They're being accompanied by police and fire department vehicles.

Once there, the remains will be transferred to an underground repository in the same building as the National September 11 Memorial Museum.

Like many decisions involving the site of the nation's worst terrorist attack, the disposition of the remains has been contentious.

A group of victims' family members say the remains should be stored in a separate above-ground monument. They vowed to protest the procession.

Other family members support the plans, which have been in the works for years.