Yemeni security forces have opened fire on protesters in the capital, Sanaa, killing at least nine people, witnesses and doctors say.
They say about 100 people were also injured in the shooting.
It comes a day after the government and opposition agreed to sign a deal soon under which President Ali Abdullah Saleh would step down within 30 days.
But many people across Yemen are angry the president will get immunity under the agreement, correspondents say.
Yemeni troops and plain-clothes police opened fire when anti-government demonstrators tried to reach an area beyond the district of Sanaa where protesters have been camped for weeks, witnesses say.
Many of the dead and wounded had gunshot wounds to the head and torso, one local doctor told the Associated Press news agency.
A number of bodies were taken to hospital.
More than 130 people have been killed by security forces and supporters of Mr Saleh since the anti-government unrest began in January.
On Saturday, the Gulf Co-operation Council (GCC) brokered a deal under which President Saleh would submit his resignation to parliament, and hand over power to his vice-president, 30 days after asking the opposition to name a prime minister to form a national unity government.
Mr Saleh's agreement to step down would also be dependent on parliament passing legislation providing immunity from prosecution for the president, his family "and those who worked with him during his rule".
Mr Saleh's General People's Congress (GPC) immediately accepted the GCC proposal, while the opposition coalition agreed on Sunday only after its leaders had received "assurances" from the GCC, the US and Europe on the transfer of power.
The deal caused a serious split between the opposition coalition and the youths who have led the demonstrations across the country for months. They accuse the politicians breaking a promise to put Mr Saleh on trial.
Some have also warned that allowing the president to stay on for another month could exacerbate the crisis in the Arab World's poorest state.