The site of the fire was cordoned off and the criminal investigation department had begun an investigation, she said.
Of the 23 people injured, four suffered burns and one was injured in a fall.
The others who were injured, including first responders and at least four police officers, were examined in hospital for possible smoke inhalation, she said.
The police were unable to provide any information on the condition of those who were injured or their age and gender.
The exact number of people injured has also not yet been finalised, the spokeswoman said.
Earlier, a festival goer from Cologne said the Ferris wheel suddenly sped up. The burning gondolas were at the very top of the wheel.
German rapper Ski Aggu was performing when the fire broke out.
“I’m absolutely shocked and upset about the Ferris wheel fire during my show at Highfield,” the rapper said in a post on Instagram.
“I was only told through my earpiece that I should not stop the show under any circumstances, but should initially continue to talk with you so [to] avoid mass panic.”
“The priority was to prevent the situation from escalating any further. Fortunately, that worked.”
A fire service spokesperson told the dpa news agency about 30 minutes after the fire broke out that the situation was under control.
The music festival at Lake Stormthal was set to be headlined by Macklemore today.
