This came in yesterday (local time) via the superb Jane Novak at her Armies of Liberation 'blog, but now the AP and AFP are running versions of the story.
The gist: Four South Korean tourists and their Yemeni guide were killed, some larger number of other tourists and locals were wounded, in a bomb explosion. The device was planted in a popular observation point for viewing the UNESCO World Heritage Site at Shibam and was apparently a command-detonated device. That means the terrorists targeted that group of tourists intentionally.
The South Korean government had put a travel warning out on citizens visiting Yemen, but it was not an enforceable prohibition.