German police arrested a 20-year-old man after he detonated pyrotechnics and threatened passengers with knives on a high-speed train traveling toward Frankfurt.Twelve people suffered injuries during the attack at Siegburg-Bonn station, with one victim hospitalized for acoustic trauma after being struck by devices filled with plastic pellets.Passengers successfully cornered the masked suspect in a restroom before authorities arrived to charge him with aggravated assault and weapons law violations.