NEWTOWN, Conn.—Police investigating the Sandy Hook Elementary School massacre here seized a small arsenal of firearms, knives and swords along with medical records and computer equipment from the 20-year-old gunman's home in the days after the shooting, court documents released Thursday reveal. Also Thursday, the state prosecutor overseeing the case said that Adam Lanza killed 26 people within five minutes of storming into the school before turning a gun on himself. The documents—85 pages of affidavits, search warrants and lists of tems seized from the car and Newtown home Lanza shared with his mother, Nancy—paint a chilling picture of the...