Non-emergency surgeries were cancelled at Peterborough City Hospital after a 30 minute power cut.
The disruption at the hospital in Bretton occurred at 4.20pm today (Wednesday, June 24).
The cause of the cut is being looked into.
Planned surgeries tomorrow are expected to go ahead.
The hospital’s energy provider is EDF.
A spokeswoman for Peterborough and Stamford Hospitals NHS Foundation Trust said: “There was a power outage at Peterborough City Hospital this afternoon that affected part of the building where our Emergency Department, Theatres, Critical Care, Neonatal Intensive Care Unit, children’s ward and women’s health ward are located.
“The Trust declared a major incident and staff responded promptly according to our tried and tested business continuity plans. The power was fully restored to all areas within 30 minutes.
“Our facilities management service provider Brookfield Services is still investigating the cause of the outage and testing the system to assure us that the power supply is stable.
“As a precaution, we have cancelled any further surgery planned for today, with the exception of any emergencies.”