Hundreds of fast food workers walked off their jobs in many U.S. cities and in more than 30 countries on Thursday, joining labor and union activists in protests calling for wages of $15 an hour and the right to seek union representation without retaliation. At least 17 food chains were targeted, including McDonald’s, Burger King, Wendy’s and KFC. No violence was reported. The day of protests, targeting the $200 billion fast-food industry at a time of intense competition, drew particular media attention in New York, Los Angeles and Chicago. They continue a campaign launched 18 months ago. Protester organizers said that a Burger King in Atlanta and another in Dorchester, Mass., were at least briefly closed during the strike, but Burger King spokesman Alix Salyers said no stores closed. Similarly, McDonald’s officials said no restaurants closed, while protesters said several did. More