Authorities in Germany say 33 people have been hurt after lightning struck a rock festival in western Germany overnight.

The Rock am Ring festival in the town of Mendig was hit by two lightning strikes early today.

Police and organizers said eight people from production teams were injured when the first strike hit the backstage area around 1 am (2300 GMT). 

Organizers later halted concerts and offered visitors shelter in large, lightning-proof tents. A little before 4 am, lightning hit the festival's camping area and another 25 people were injured. 

Police say all of those injured have been taken to hospitals for observation and are in good health. None suffered a direct hit by lightning. The festival is going ahead as planned.