Up to 25 years of cancer research has been saved from a fire in a building next to the Christie cancer hospital.
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, praised the fire service for helping them to rescue "incredibly important" tissues and samples from the centre.
He assured Christie patients the fire would have "no impact" on their care.
'Watch and wait'
"We are largely a discovery centre so most of the samples we collect are to try and understand what is happening in the patient rather than to direct patient care," Mr Marais said.
He said the institute was "very grateful" and "very happy" the fire service helped it salvage tissues and samples stored in large freezers at temperatures of -80C (176F), as well as samples stored in liquid nitrogen at -200C.
He said there was "not much fire damage but a lot of water damage", although the building's concrete floors had limited it.
Six fire engines remain at the scene and firefighters are still tackling pockets of fire in the roof of the Paterson Building in Wilmslow Road, the fire service said.
Firefighters are expected at the site for a further 48 hours and Wilmslow Road remains closed.
No-one was hurt in the blaze and the Christie hospital is operating as normal.
The cause of the fire has not been established but earlier the fire service said a more detailed investigation would take place.
The BBC understands maintenance work had been taking place on the roof of the affected building before the fire started.
Mr Marais spoke of the horror of witnessing the blaze unfold.
"It was shocking… all one can do is watch and wait as it develops."
He said the institute was very concerned about any research it may have lost and so were "PhD students, post-doctorate fellows and group leaders carrying out experiments which were abruptly ended".
- The Christie is the largest single-site cancer centre in Europe
- It is rated as 'Outstanding' by the Quality Care Commission
- The Cancer Research UK Manchester Institute's building is attached to the Christie hospital
- A proton beam therapy centre is currently under construction at the hospital
Emergency meetings were held on Wednesday and would be held again to establish which parts of the building could still be used, and find alternative arrangements for parts that could not, Mr Marais said.
"You only have to look at the building to realise we are not going to be able to occupy the building."
"People are very worried about their careers and research but ultimately this is about patients.
"We owe it to the patients to get going again as quickly as possible.
'We will rebuild'
"It is a very important institute for Manchester... and for the country and internationally."
He said he had assurances from Nancy Rothwell, president of the University of Manchester, Roger Spencer, chief executive of Christie hospital and Harpal Kumar, chief executive of Cancer Research UK, "that we will work through this and come back and rebuild".
He added: "We aim to understand cancer biology and then use that to [constantly] improve patient care so we are keen to get going as soon as possible."
The Christie is the cancer hospital for most of the North and part of the Midlands and treats more than 40,000 patients a year.