Police in Yemen used tear gas, water cannons and live bullets at anti-government protesters at a protest camp in Tahrir Square in the center of the capital, Sanaa. At least six people died and about 1200 were injured.
Reports say hundreds of police moved in, where protesters have been camping out in Sanaa’s Tahrir Square for weeks.
The clashes came after the US urged opposition groups to take up President Ali Abdullah Saleh’s call for talks.
Weeks of protest against Saleh’s 32-year rule have left about 30 people dead.
Police were blocking medical teams from entering the area.