Eight people are being treated in A&E following a suspected chemical leak at a hospital laboratory.
More than 20 firefighters and police officers are currently at Addenbrooke's Hospital in Cambridge after an "unconfirmed substance" spill in a plant room.
An employee said they were working when 'someone told them they needed to get out'.
Emergency services rushed to the internationally renowned research centre at about 11.20am today and a cordon is in place around the main entrance to the A&E unit.
Cambridge University Hospital (CUH) earlier tweeted to confirm the incident and said the labs have been "evacuated".
They wrote: "Lab evacuated as precaution. At 11.20am today our Operations Centre received a report that an unconfirmed substance had been spilled in our laboratory block.
"@cambsfrs was contacted and as a precaution, the building was evacuated.
"Currently no patient services are affected."
As yet the cause of the leak is unknown.
One woman, who works at the hospital, told Cambridge Live: "We were just working and then someone told us that there was a chemical spill and we needed to get out.
"The fire alarms were going off.
"We're just waiting now so we can get our belongings. We didn't panic.
"This is the first time this has happened in around 10 years."
Cambridgeshire Fire and Rescue tweeted: "We currently have more than 20 firefighters, including crews from Cambridge, St Neots and Newmarket from Suffolk at the scene of an incident at Addenbrookes Hospital in Cambridge.
"Firefighters are working with on site staff and other emergency services."
