"According to current information a 27-year-old Swiss man poured out a flammable liquid. He was also armed with at least one knife. The liquid caught fire," St. Gallen cantonal police said in a statement.

It said the injured were taken to various hospitals with burn and stab wounds, and that the assailant was also injured in the incident and transported to hospital.

The attack occurred at 2:20 p.m.