A 32-year-old woman was arrested after a knife attack on a bus heading to a festival in western Germany injured six people, three of them critically, authorities said Saturday. Officials said there is no evidence of a political or religious motive.

The attack took place Friday evening in Siegen, a town east of Cologne, as the bus was en route to a local festival. Police said about 40 other passengers were on board when the assault happened around 7.40 pm.

The six people wounded, aged 16 to 30, were all from the region. By Saturday morning, three had been released from the hospital after outpatient treatment, police and prosecutors said.

Local authorities said the festival would go ahead as planned.

The stabbing in Siegen came a week after another knife attack in Solingen, a city in the same state of North Rhine-Westphalia, in which a suspected Islamic extremist from Syria, who had avoided deportation, allegedly killed three people and wounded eight others. The Solingen attack prompted the governing coalition to propose tighter knife laws and easier deportation processes.

Police said the woman arrested in Siegen is a German citizen with no immigrant background.