Children were among 19 people rescued from a fairground ride which became stuck 20 metres above the ground.
Firefighters spent more than three hours retrieving 13 adults and six children from the attraction on the South Bank in central London on Sunday night.
There were no reported injuries and it is not known what caused the ride - which has capsules that swing around a central pillar - to stop working.
London Fire Brigade (LFB) used two cherry-picker-style aerial platforms to bring people down from their seats in an operation that lasted several hours.
Crews also worked with an onsite engineer to manually release the ride's friction brake so that it could be turned around and aligned with the aerial ladder.
LFB station manager Clive Robinson said people on board had waited patiently to be rescued.
"It was slow work as we need to access each cage on the ride individually and ensure they were secure before we move them from the ride onto our platform and bring them back down to the ground," he said.
"There were no injuries and everyone was patiently waiting for us to get around to them.
"While everyone was very relieved to be back on the ground, everyone was very calm."
A spokeswoman for the Health and Safety Executive said: "We are aware of the incident and we are making inquiries."
Officers from the Metropolitan Police placed a cordon around the ride to ensure the fire brigade could carry out their work away from crowds.