Yemeni security forces have killed four people and wounded hundreds more in the second day of a harsh crackdown on anti-government protests, witnesses said. One of the dead was a 15-year-old student.

The assault with gunfire and tear gas was the toughest yet by the government in a month of protests aimed at unseating the president, Ali Abdullah Saleh, who has been in power for 32 years. An ally in the Obama administration’s fight against al-Qaida, Saleh had appeared to be one of the Arab leaders most threatened by the regional unrest inspired by revolts in Egypt and Tunisia. …

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