The Rock am Ring music festival at Germany's famous Nürburgring race track was interrupted on Friday by police based on a terror alert.
Authorities ordered the more than 10,000 people gathered at the track in the western city of Nürburg evacuated pending an inspection of the site, Efe reported.
Festival organisers agreed to cancel Friday's performances after police issued the alert roughly six hours after the start of the three-day event.
Police said the alert was based on "concrete indications" that made it impossible to exclude "a possible terrorist threat."
The government of Rhineland-Palatinate state confirmed that an alert was in effect, but did not provide any further details. Police established a telephone number for festival-goers seeking information.
Launched in 1985, Rock am Ring takes place annually at the Nürburgring and some 85,000 people were expected to attend this year's edition.