Six fire crews were called to deal with a ‘large hazardous materials incident’ at the Royal Preston Hospital on Friday night.
It involved a chemical leak in a pathology lab at the hospital in Sharoe Green Lane, Fulwood, Preston.
Crews wearing breathing apparatus and gas tight suits identified that the leak was Formaldehyde and worked to stop it.
Firefighters then laid down absorbent pads.
There were no casualties and no risk to patients or staff. A small number of staff were evacuated.
The drama unfolded at around 8.10pm on Friday and the clean up operation lasted several hours with crews remaining at the hospital into the early hours of Saturday morning.
Volunteers from the North West Blood Bikes spent the night assisting the emergency services.
An investigation into how the leak occurred with now be carried out by hospital bosses.
A spokesman for Lancashire Teaching Hospitals NHS Foundation Trust said: “We can confirm that there was an accidental spillage in the pathology laboratory at Royal Preston Hospital on Friday evening.
“As is standard protocol we evacuated a small number of staff from the laboratory, and contacted Lancashire Fire and Rescue Service which attended the hospital to assess the situation and help us resolve the matter quickly.
“A clean up operation took place during the night and the laboratories are now operational.
“We made alternative arrangements during this period to maintain the service and there was no risk to patients or staff.
“We would like to thank our colleagues at Lancashire Fire and Rescue for their prompt response and assistance.”