More than 20 people were injured after a Ferris wheel at a music festival in Germany caught fire on Saturday evening.

Images show two carriages of the ride on fire as smoke billows into the air at the Highfield Festival near the city of Leipzig.

According to a statement from Saxony police, the ride caught fire shortly after 9 p.m. local time, for reasons that are still unclear.

Four people suffered from burn injuries due to the incident, the statement said, while another was treated for injuries from falling.

According to the statement, 18 people including first responders, police officers and others on the ride came into contact with smoke and were taken to hospitals for medical treatment.

Police have launched an investigation. The scene of the incident has been cordoned off.

German rapper Ski Aggu was performing onstage at the festival when the Ferris wheel caught fire. He later took to his Instagram stories to write that he was “dismayed and shocked” over the night’s events.

He added that he was told in his ear that he should “not cancel the show under any circumstances” but rather maintain dialogue with the crowds to avoid any mass panic.