Four people have been arrested over damage to cables that left a hospital's emergency department without power.
Ambulances were diverted from The Queen Elizabeth The Queen Mother Hospital (QEQM) in Margate and patients were urged not to attend A&E during Wednesday's shutdown.
Some patients were also moved during the alert, between 19:00 and 23:00 GMT, after electricity lines were damaged.
The men have been arrested and taken into custody by West Midlands Police.
Staff at the Kent hospital had to move patients to unaffected areas after cables connecting the back-up emergency generator, as well as the main power supply to part of the building, were damaged during what the hospital said was an attempted theft of cables.
It said back-up systems for critical equipment maintained a power supply and Kent Fire and Rescue teams provided emergency lighting while staff moved the patients.
Ambulances that would otherwise have taken casualties to the QEQM Hospital were instead sent to the William Harvey Hospital in Ashford, nearly 40 miles away.
A spokesman said: "Staff were able to repair the damaged cables and reinstate power just before 11pm and the staff on site worked quickly and safely to return to normal operating."