Southern Sudan’s minister of defense, Dominic Dim, and a presidential adviser, Justin Yak, were among at least 23 people killed in a plane crash near the southern town of Rumbek, officials of the southern government said. The authorities blamed engine failure for the crash. The plane, a Beechcraft 1900 operated by South Sudan Air Connection, had 21 passengers on board. Nineteen of those aboard were military officials, The Sudan Tribune, a local newspaper, reported.