The collapse of the towers spread dust across New York City and left hundreds of thousands of tons of debris at the site. To organize the cleanup and search for survivors and for human remains, the New York City Fire Department divided the disaster site into four sectors, each headed by its own chief. Cleanup workers trucked most of the building materials and debris from Ground Zero to Fresh Kills Landfill in Staten Island. Some people, such as those affiliated with World Trade Center Families for Proper Burial, were worried that human remains might also have been inadvertently transported to the landfill.