Thousands of Yemenis defiantly demonstrated Wednesday at a public square, a day after the army stormed Sanaa University, firing live ammunition, killing one person and wounding scores of others.
The attack escalated tensions in Yemen, which has been rocked by weeks of protests against President Ali Abdullah Saleh, a key U.S. ally in the campaign against al-Qaida who has been in power 32 years.
Abdullah al-Jeifi, 24, died and several other protesters who were shot in Tuesday's raid were in serious condition, said Mohammed al-Abahi, one of the doctors volunteering at the Sanaa University campus. Soldiers also used rubber bullets and tear gas in their assault.
Outraged at the government raid, more protesters camped out in tents near the university and on campus Wednesday. A group of young protesters issued a "black list" with the names of 13 officials they say are responsible for the violence against peaceful protesters. The names include the son of President Ali Abdullah Saleh who heads the Republican Guards, the interior minister and other top security officials.
The statement vowed revenge against those they called "criminals" and pledged to continue with the sit-in until they topple the regime. Thousands of people also protested in the southern port city of Aden and on the streets of Ibb province.
Human rights groups and the U.S. criticized Yemen's crackdown on protests Wednesday.
In Washington, State Department spokesman Mark Toner called on both sides to show restraint. "We urge the government of Yemen to investigate and hold accountable those who appear to have utilized excessive force," he said.
"These disturbing heavy-handed tactics used with lethal effect against protesters must stop immediately. People must be allowed to assemble and protest in peace," said Philip Luther, Amnesty International's deputy director for the Middle East and North Africa.
Human Rights Watch also issued a report, saying Yemeni security forces killed at least nine people and injured 150, some of them children, during peaceful protests in the southern city of Aden last month.
"Shooting into crowds is no way to respond to peaceful protests," said Joe Stork, deputy Middle East and North Africa director at Human Rights Watch.
Yemen's Interior Minister, Gen. Mouthar al-Masri, told reporters Wednesday night that gunfire from the rooftop of a building near the university led to the clashes.
Students at Sanaa University have been sleeping on campus since mid-February, shortly after the start of the protests calling on Saleh to step down. In an escalation, soldiers stormed the campus late on Tuesday, shooting live ammunition, rubber bullets and firing tear gas. About 90 protesters sustained gas inhalation and minor injuries in the raid.
"This aggression is an indication that the regime is collapsing and cannot stand before the youth revolution," said Mohammad Qahtan, a spokesman for the opposition.
Witnesses said the mayor of Sanaa, Abdul-Rahman al-Akwa, who is also the brother-in-law of Saleh, led a group involved in the raid.
Medical officials said at least two of the wounded were in serious condition. Rabih al-Zuraqi, 25, was suffering from brain hemorrhage while 18-year-old Jamal al-Buhaisi suffered complications from a bullet wound to the shoulder. A few others had breathing problems due to smoke inhalation.
Hosni al-Jushai, a doctor at the Science and Technology Hospital who was volunteering with the protesters, said it appeared from the symptoms that security forces used banned nerve gas against the demonstrators, in addition to tear gas.
In a separate incident Wednesday, bodyguards of lawmaker Mohammad Abdel Illah al-Qadi exchanged fire with a security patrol in Sanaa. Al-Qadi's brother and a bodyguard were wounded.
Al-Qadi, a longtime stalwart of Saleh's regime, said he was resigning from the ruling party last month and joining the opposition.
It was not clear what triggered the clash.
Even before Yemen was hit by the wave of protests, the country was growing increasingly chaotic with a resurgent al-Qaida, a separatist movement in the south and an off-on Shiite rebellion in the north vexing the government.
In an attempt to quell escalating protests, the president called for national dialogue after meetings Monday with the country's political and security chiefs. The state-run news agency said the conference would be held Thursday and would include thousands of representatives from across Yemen's political spectrum.
But opposition leader Yassin Said Numan said there would be no dialogue unless Saleh agreed to step down by year's end.
Saleh's pledge not to run for re-election in 2013 has failed to defuse the protests, as have his calls for a unity government with opposition figures.