Back-up generators at an Adelaide hospital failed during South Australia's widespread power outage, forcing 17 patients to be transferred to another hospital.
Some needed help breathing with manual respirators as they were taken from Flinders Medical Centre to Flinders Private Hospital on Wednesday night, health officials have revealed.
The back-up power failure was caused by a broken fuel pump despite the system being tested earlier in the week.
"We did have generator power for about an hour, at which point the generators stopped," SA Health acting chief executive Vicki Kaminski told reporters on Thursday.
Life-supporting machines reverted to battery power when the generators cut out.
Ms Kaminski was adamant no lives were at risk both at the hospital and during the patient transfer.
"All of the life-saving equipment is on battery back-up and has many hours of battery," she said.
She said the fuel pump issue could not have been predicted and was discovered and repaired quickly.
The Royal Adelaide Hospital's generator system functioned properly during the state-wide blackout.
Power has returned to medical centres in Adelaide but some country hospitals are still running on generators.
Elective surgeries scheduled on Thursday have been postponed at some hospitals across the state as demand on health services remains high.