Festival goers leave the venue of the Rock am Ring music festival in June 2, 2017 in Nuerburg following an evacuation alert amid a possible "terrorist threat". [Photo/VCG]

FRANKFURT - German rock music festival "Rock am Ring" in the western German city of Nuerburg was interrupted Friday evening due to "concrete evidence of terrorist threat", with thousands of rock fans being evacuated from Nuerburgring circuit, said the local police.

The state government of Rhineland-Palatinate has also confirmed the terror threat.

The festival which kicked off Friday would as planned extend over three days, however, it remains to be assessed if the festival would resume from Saturday onwards, told Roger Lewentz, interior minister of the state Rhineland-Palatinate.

"Tomorrow we will make decision about how it goes on." He said, added that further information is due to be released at 11 a.m. on Saturday.

The investigation remains in full swing currently with a few points to be followed, as the festival grounds are being examined closely, according to the interior minister.

In view of the recent attack on a concert in Manchester, Britain, the safety concept for "Rock am Ring" had been modified in advance and the number of the emergency forces increased significantly to around 1,200.

For over 30 years, the "Rock am Ring" festival has drawn tens of thousands of music fans to the Eifel region in Germany. Festival-goers descend onto a field near a race track each year for the three-day event, set up their tents, and consume lots of beer.

Around 90,000 visitors are expected to enjoy the festival this year.

Supporting the investigation, the organizers still hope the festival would continue Saturday, saying that all visitors will be kept informed of any developments on all "Rock am Ring"social media channels, radio and the speakers.