Earlier today North and South Korea engaged in a cross-border clash. The North fired on the island of Yeonpyeong, shelling the area for about an hour. According to the South Koreans two Marines were killed and four civilians were injured in the attack.
The South returned fire while around 1,600 residents on the island fled for shelter. Both sides have claimed the other fired first.
Prior to the engagement, North Korea sent a message to the South saying they would not "just sit back" while the South Koreans conducted live fire military exercises - the annual Hoguk drills.
Global Voices has an interesting round up of Twitter updates circulating in South Korea in response to the skirmish. Lee Yoo Eun, has picked out a number of tweets and translated them into English giving a flavour of the discussion online:
"Just seconds after the news broke, South Koreans tweeted madly regarding possible future scenarios and evacuation plans, as well as re-tweeting news updates.
"Many scoured for accurate sources, as some unconfirmed rumors, such as North Korean leader Kim Jong-il had died, circulated online.
"Twitterers, quoting friends in the army, said the Korean peninsula was in a near-war situation. South Korea's presidential office, Cheongwadae (@BlueHouseKorea) has tried to calm public sentiment."
