Yemeni security forces stand guard in a street of the capital Sanaa on February 23, 2014 as authorities tighten security measures after gunmen have shot dead an intelligence officer the previous day in Yemen’s southern Shabwa province. The gunmen opened fire late on February 22 at State Security Colonel Ahmed Hashim in the city of Ataq before fleeing, the official said, adding that he died instantly. AFP PHOTO/ MOHAMMED HUWAIS