Yemeni security forces opened fire on thousands of demonstrators in the southern port city of Aden after Friday's Muslim prayer services, wounding at least 19 people, in the latest confrontation with crowds pressing for the U.S.-backed president's ouster.
Tens of thousands of protesters marched in different parts of the country, and the government's response in Aden was the most violent. Medical officials said three of the 19 were seriously wounded. Two others were wounded earlier in a barrage of tear gas and rubber bullets.
Yemeni troops closed roads leading to the city with tanks and armored vehicles after it became clear President Ali Abdullah Saleh's opponents were planning massive demonstrations. Still, many made it to the demonstration.
In the capital of Sanaa, witnesses said the protesters poured into a square near the main gates of Sanaa University for demonstrations amid tight security.
Security forces were trying to thwart protesters from converging in the square that has been a flash point for weeks of demonstrations demanding that Saleh, in power for 32 years, step down.
A Muslim imam who led a Friday prayer service in the capital urged protesters to step up their demonstrations "until the president has departed."
"Every Yemeni is religiously and duty-bound to work to topple this regime," said imam Abdullah Fatir in his sermon, adding that Saleh "is a devil who has driven us to the stone ages." Shouts from the crowd of "Allahu akbar," or "God is great," accompanied his words.
Participants said tens of thousands attended -- perhaps one of the largest gatherings since the protests began earlier this month. Violent clashes accompanied protests one week ago -- also after Friday prayers -- in Sanaa and the southern cities of Aden and Taiz, with several deaths reported.
Some of the demonstrators in the latest protests tried to break the security lines and move to other streets, but police fired into the air and forced them to backtrack.
"We are coming to take you from the presidential palace," activist Tawakul Kermal told the gathering, addressing Saleh.
Other demonstrations were staged in Taiz and Hadramout.
On Wednesday, Saleh said he had ordered his security services to protect protesters, stop all clashes and prevent direct confrontation between government supporters and opponents.
Yemen, an impoverished country with a weak central government and an active branch of al-Qaida, has been swept up in the protests inspired by successful uprising in Egypt and Tunisia. Saleh has promised to step down after national elections in 2013, but the demonstrators want him out now.
In recent days, students and other activists have been digging in, setting up encampments in some public areas.
Government forces failed to dislodge the protesters in the capital, and thousands more have streamed into the square at the center of the protests, including academics, writers and artists.