Iraqi security forces inspect the site of a bomb attack at a police checkpoint on a highway near the southern Iraqi city of Nassiriya on Sept. 14. BAGHDAD—Islamic State gunmen stormed a restaurant in southern Iraq after blowing up a car bomb outside, killing more than 50 people, Iraqi officials said, including Iranian pilgrims having a meal. Thursday’s attack, along a highway near the southern city of Nassiriya, was one of the deadliest in the country in recent months and comes as Islamic State’s days of ruling over vast areas of Iraq near an end. The Sunni Muslim extremist group claimed the assault in a statement, saying three groups of fighters clad with explosive belts had killed dozens of “rejectionist idolaters”— slurs it uses to denote Shiite Muslims. An interior ministry official said a bomb had first exploded in the restaurant parking area. Gunmen disguised as members of Iraq’s […]