MUNICH — At least three people are dead and eight others were injured, five of them seriously, in a knife attack Friday in the western German city of Solingen, where a celebration of the city’s anniversary had been taking place, officials said.

“This evening we are all in shock, horror and great sadness in Solingen. We all wanted to celebrate our city’s anniversary together and now we have to mourn dead and injured people,” Mayor Tim Kurzbach said in a statement Friday night.

The…