Cautious calm prevailed in most of streets in the Yemeni capital Sanaa and most of the cities after a day that witnessed the country's worst militant assault in 18 months. On Thursday, a suicide bomber and gunmen wearing army uniforms attacked Yemen's defense ministry, killing 52 people including foreign medical staff, according to government sources. The coordinated strikes wounded 167 people, said the Yemeni government's security committee. Two German and two Vietnamese doctors and one Indian and two Filipino nurses were among the dead, it added.