Four people have been injured during an educational event about chemistry in Denmark, police reported on Saturday. An explosion occurred during a performance in a library in Tønder, a small town near the southern border to Germany. A 22-year-old man assisting in the show was seriously injured and hospitalized alongside two children who sustained minor injuries. The third child only suffered minor bruises, the police report said. Some 40 people attended the show, which was advertised as a family event to present the possibilities of chemistry. The contents of a glass container exploded, accordi…