government protester reacts along with other women and children following clashes with Yemeni police in Sana'a Saturday. (AP) SANA'A: Yemeni security forces killed six people Saturday and wounded hundreds on the second day of a harsh crackdown against 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 Yemeni government in a month of protests aimed at unseating President Ali Abdullah Saleh, who has been in power for 32 years. The violence began with a pre-dawn raid on a central square in the capital, Sanaa, where thousands of pro-democracy protesters have camped out. Doctors and eyewitnesses said security troops surrounded the square with police cars and armored personnel carriers shortly after midnight and began calling on protesters through loudspeakers to go home. At 5 A.M., security forces stormed in, firing live and ammunition tear gas. One protester died from a bullet to the head, which may have come from a sniper on the rooftop of a nearby building, witnesses said. Abdelwahed Al-Juneid, a volunteer doctor working with the protesters, said around 250 people were wounded. A few hours later, another protester was shot dead in a nearby street. Eyewitnesses said he was also killed by a sniper, but that could not be independently confirmed. Security officials did not have any immediate comment. In the city of Dar Saad in the southern province of Aden, police used live fire and tear gas to disperse a crowd of several thousand, killing three demonstrators, a local activist and a hospital official said. They spoke on condition of anonymity because of the tense situation. The hospital official said all the dead were all shot in the head. Eleven other protesters were wounded, he said. The activist said the protesters later marched to the local police station, demanding that the shooter be handed over. Then they burned down the police station, the witness said. Dozens of demonstrators were apparently overcome by volleys of police tear gas. “The gas used by the police is strange. It causes cramps and a collapse of the nervous system,” said Bashir Al-Kahli, a doctor helping the injured. The Interior Ministry denied using any sort of nerve gas.