
Sanaa, Yemen (CNN) -- A Yemeni man injured in protests at Sanaa University died of his wounds early Wednesday morning, a medical official said.
Mohamed Ali Mutlak, 24, was among dozens of anti-government demonstrators wounded Tuesday when security forces fired into the air and shot tear gas into a crowd of tens of thousands of protesters who had massed in front of Sanaa University, witnesses said.
Eight of them were still in critical condition, said Dr. Waseem Qurashi, head of the medical department at Change Square, Sanaa University.
According to witness Ala'a Al-Khowlani, at least 40 anti-government demonstrators were wounded and at least one of them was in critical condition. Other witnesses put the number of wounded as high as 67.
Protests took place across the country Wednesday, witnesses said, but there was no word of violence.
Tens of thousands of anti-government demonstrators were outside Sanaa University. In Taiz, tens of thousands of protesters continued their sit-in protest, calling for Saleh's ouster. Thousands were also in the streets of Ibb, Aden, Hodeidah, and Dhamar.
However, the recent casualties drew condemnation. Amnesty International on Wednesday urged Yemeni authorities to "end deadly night raids and other attacks on protests."
"This is the second time in three weeks that protesters have been killed in late night raids by the security forces in the capital," said Philip Luther, Amnesty International's deputy director for the Middle East and North Africa.
"These disturbing heavy-handed tactics used with lethal effect against protesters must stop immediately. People must be allowed to assemble and protest in peace."
Amnesty said about 30 people have reportedly been killed in Yemen in the "ongoing unrest which began early last month."
Mohammed Abulahoum, a senior government official, Wednesday condemned "the acts of violence used by the police and the military last night against civilian protesters outside the university.
"There was no need for that force. This will only escalate the tension between both sides," he added.
He also rejected the official government explanation that tribesmen had tried to sneak arms into a no-weapons zone.
"They had no arms with them and they had no intention of using arms," Abulahoum charged, saying he knows those tribesmen.
Yaser Al-Hasani, one of the demonstrators, said security forces cracked down after students defied their orders not to take food and blankets into the protest area outside the gates of the university. The supplies were intended for the thousands of anti-government demonstrators who have camped out calling for Saleh to step down.
In a statement e-mailed to reporters, the government blamed the violence on people who had tried to sneak weapons into a "weapon-free area" outside the university, then resisted arrest.
"The suspects resisted arrest and soon thereafter a gun fight broke out, injuring dozens of suspected militants, policemen and innocent bystanders," a government statement said. "Panic from the shootings set off a raging stampede in the area. There is no official confirmation on casualties at this point."
The government said early Wednesday that the situation was under control and that the Interior Ministry would investigate the incident.
Yemen's anti-government demonstrations are unfolding in a nation wracked by a Shiite Muslim uprising, a U.S.-aided crackdown on al Qaeda operatives and a looming shortage of water.
High unemployment fuels much of the anger among a growing and impoverished young population. The protesters also cite government corruption and a lack of political freedom.
Saleh, who has refused to step down, has said he will not run again for the presidency in the next election.
CNN's Christine Theodorou, Mohammed Jamjoom and journalist Hakim Almasmari contributed to this report