The plain-clothes men, believed to be security officers, fired from rooftops at protesters demanding an end to more than three decades of President Ali Abdullah Saleh’s rule.
“There were 35 people with gunshot wounds, three of whom are in an intensive care unit,” a hospital doctor told Reuters by phone.
Three people were killed and 15 wounded on Friday when troops shot at protesters in Ibb, a city south of the capital Sanaa. The killings pushed the overall death toll since protests began to at least 170.
Security forces on Saturday arrested Ahmed Al Musaibli, a leading broadcaster who had left state television to work for an opposition satellite channel, witnesses said.
In the central town of Rada, gunmen shot dead six soldiers and wounded seven in an attack on a checkpoint on Friday, a local official said, blaming Al-Qaeda.
Yemen faces violence from separatists in its south, rebels in the north and insecurity caused by tribalism and poverty.
