Police in south-west Germany are investigating after an 18-year-old spectator suffered second-degree burns at an annual "witches' parade".
Some witnesses said that the woman was carried to a cauldron in jest before being thrown knee-deep into hot water.
Others present reported the woman was held over the cauldron at the carnival in Eppingen on Saturday, police said.
The screaming woman was abandoned at the roadside by the "witches", reports the BBC citing police.
She was later taken to hospital.
Police say they have secured the cauldron involved, which was heated over a wood-burning stove, all carried on a cart.
Some of those who were part of the group of witches have been identified, the police statement said.
The witches' guild of Eppingen, which organises the event, said it was deeply shocked by the incident.
The parade has been running since 2003.