At least 34 people were injured in the accident on a roller coaster at Legoland in Günzburg, Swabia, two of them seriously.
A police spokesman said on Thursday the German Press Agency.
A police spokesman said a roller coaster train braked sharply on Thursday and another train drove up to it.
The injured suffered bruises and abrasions, among other things.
According to a spokeswoman for Legoland, the accident happened on the "Fire Dragon" roller coaster.
All available rescue workers at Legoland are on duty.
According to the spokeswoman, several people are still in the wagons.
A large number of police and rescue workers were on site to get them out.
Further details initially remained unclear.
Deadly thrill
The “Feuerdrache” roller coaster first leads through a covered, darkened area of the park.
In the course of the ride, you then go in the fresh air over a stretch with slopes and a few curves.
According to park information, the roller coaster travels at speeds of up to eight meters per second, which corresponds to around 29 kilometers per hour.
Last Saturday there was a fatal incident on a roller coaster ride in an amusement park in Klotten on the Moselle in Rhineland-Palatinate.
A 57-year-old woman fell out of the moving attraction.
She suffered fatal injuries.
It is still unclear why the woman fell off the roller coaster.
Despite all safety measures and technical measures: Fatal accidents with roller coasters or in amusement parks may be rare, but they attract special attention when the thrill ends in death.
In mid-July, a 14-year-old girl died in a serious accident on a roller coaster in Aarhus, Denmark.
In September last year, a six-year-old fell off a roller coaster at a Colorado amusement park.
She wasn't buckled up properly.
And in June 2016, for example, ten people were injured when a roller coaster derailed in Scotland.