The vital work of Manchester's cancer research centre will be "delayed" as experts assess the full damage of the blaze which tore through it this week.
The fire at the Cancer Research UK Manchester Institute in Withington started at 10:35 BST on Wednesday.
Prof Richard Marais, director of the institute, said they were still counting the costs of the damage.
But he said staff were "determined" to get back to work "as soon as we can".
Prof Marais told the BBC the fire would "have an impact" but added: "I have been blown away by the response we have had from the people who work here.
"Yes, it will delay us but we have a fantastic group of people who are determined - the reason they came here is because they wanted to improve patient care. "
Up to 25 years of cancer research has been saved from the fire in a building next to the Christie cancer hospital.
Prof Marais said they would have a clearer indication in the next few days exactly what equipment - including a "supercomputer" - had been damaged and what data and chemicals had been lost.
He previously assured Christie patients the fire would have "no impact" on their care.
The fire service helped the centre to salvage tissues and samples stored in large freezers at temperatures of -80C (176F), as well as samples stored in liquid nitrogen at -200C.
Firefighters were still tackling pockets of fire in the roof of the Paterson Building in Wilmslow Road 24 hours after the blaze broke out.
The cause of the fire has not yet been established.
The BBC understands maintenance work had been taking place on the roof of the building before the fire started.
Cancer Research UK is appealing for donations.