Nurses were trapped in Croydon University Hospital overnight as rioters smashed windows and lit fires just metres away.
London Road in front of the hospital was closed as a result of disturbances, including arson attacks, which began early on Monday evening, close to the shift change-over.
The road closure and the riots in surrounding areas near the homes of nurses and other staff members meant many were unable to get home after the day shift and others were unable to get into work. About 15 staff slept over while many more worked a double shift to keep services running.
About 20 inpatients ready for discharge and more who would not normally have been admitted from accident and emergency were also unable to leave, forcing the trust to open extra beds.
However, in common with other areas that saw riots, the disturbances did not lead to a significant increase in A&E attendances.
Richard Parker, director of acute operations at Croydon Health Services Trust, paid tribute to the hard work of staff.
He said: “Some of our staff had some very frightening experiences. A gang came down the London Road and looted the betting shop about 100 metres away. We were on standby for a major incident but the main problem was getting people out because we were in the thick of it.”