Witnesses say Yemeni police have fired bullets and tear gas at anti-government protesters in the southern city of Aden, injuring at least seven people.
The incident took place on Saturday, a day after dozens of people were killed in a protest in the capital, Sana'a. Medical officials said Saturday the death toll from Friday's government crackdown in the capital had risen from 40 to 52 people. Medics and witnesses say more than 100 people were wounded.
The Reuters news agency says two prominent members of Yemen's ruling party resigned on Saturday in protest of the killings. Shortly after Friday's crackdown, Yemeni President Ali Abdullah Saleh declared a nationwide state of emergency. News reports say military forces have set up checkpoints and barricades in the capital.
On Thursday, at least 85 people were reported wounded after Yemeni security forces and government loyalists clashed with protesters.
World powers have criticized the violence.
Yemenis angered by poverty, corruption and a lack of political freedoms began demonstrations earlier this year.
Saleh also faces a challenge to his authority from al-Qaida militants, who have based themselves in lawless parts of Yemen to plot attacks on the government and the West.
Some information for this report was provided by AP, AFP and Reuters.