Reports from Yemen say at least five protesters were wounded in an overnight attack by masked men on a sit-in in the capital, Sanaa.
Witnesses said the attack on demonstrators in a central square was carried out by men wearing masks and using guns, clubs, and knives.
Protests across Yemen against President Ali Abdullah Saleh's 32-year rule have been marred by violence that has left some 40 people dead.
Dozens of people were reported wounded on March 16 when security forces used tear gas and fired live rounds on antigovernment demonstrators in the western port city of Al-Hudaydah.
compiled from agency reports