Oxfordshire Fire & Rescue Service continued the search despite the fact they had not “picked up any signs of life from our listening devices.”
Chief Fire Officer Dave Etheridge, Oxfordshire Fire & Rescue Service, said: “We remain committed and determined to return the missing people to their families, and work continues overnight.
“We are working with structural engineers and demolition experts to establish a safe way of working on site. In addition the military is supporting the search for the missing people.
“They will be using a mini remote control vehicle to assist with the search for survivors at the site.
“This provides us with enhanced capability and their equipment and expertise will be invaluable.”
Thames Valley Police Assistant Chief Constable Scott Chilton said: “We are continuing to work with the Health and Safety Executive and all the emergency services to understand the cause of this incident.”
South Central Ambulance Service remains on site to deal with any recovered casualties.
Coleman and Company was preparing the boiler house building for demolition when the structure collapsed on Tueasday