DALLAS (AP) — The people killed in a shooting at a mall near Dallas include two elementary school-age sisters, a couple and their 3-year-old son, a young engineer and a security guard. Andria Gaither, assistant manager at the mall’s Tommy Hilfiger store, said she was devastated to learn that one of the dead was Christian LaCour, a 20-year-old security guard who previously worked at the clothing store and often stopped in to chat. Associated Press writers Michael Balsamo in Washington, Terry Tang in Phoenix and Audrey McAvoy in Honolulu contributed