with more. what do we know? >>reporter: north korea is accusing the south of using their citizens as human shields on the island that it shelled this week. tuesday's bombing killed four people, two marines and two civilians. today, crews constructed shelters on the island for those who lost their homes. the north declared that south koreans are to blame claiming seoul took the "in humane action of using civilians as a human shield surrounded by artillery," and hyping the casualties for pop green. -- approach began da. and a south korean commander promised his troops would take "1,000 felt revenge against the north," and that was echoed as protesters demanded tougher action against north korea. and washington and seoul have pressed china, the only ally, to restrain north korea and hillary clinton calling the chinese foreign minister yesterday but so far china has only called on all sides to show restraint.