Dozens of anti-government demonstrators were 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.
According to 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 total number wounded as high as 67.
"Live bullets are being shot -- we do not know from which angle," said Yaser Al-Hasani, one of the demonstrators. "The security forces are using force against us because we are bringing in food into the protest area."
Al-Hasani said security forces cracked down after students defied their orders not to take food and blankets into the protest area outside the gates of Sanaa University. The supplies were intended for the thousands of anti-government demonstrators who have camped out in front of the university calling for President Ali Abdullah Saleh to step down.
Al-Khowlani described a similar scene.
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.
"Late Tuesday evening, during a routine police inspection on Al-Hurriya street in Sanaa, police discovered individuals with a stash of fully automatic rifles hidden inside thick blankets and camping equipment," the statement said. "The individuals were attempting to enter the 'weapon-free area' of University Square, where anti-government protesters have been camping for days.
"The suspects resisted arrest and soon thereafter a gun fight broke out, injuring dozens of suspected militants, policemen and innocent bystanders. Panic from the shootings set off a raging stampede in the area. There is no official confirmation on casualties at this point."
It said early Wednesday that the situation was under control and that the Ministry of Interior would investigate the incident.
Tens of thousands of protesters also demonstrated in the city of Taiz and thousands demonstrated in Ibb, witnesses said. Both cities are south of Sanaa.
Another demonstration -- this one at Sanaa Central Prison -- erupted Monday evening when inmates gathered in the main hall, said a prisoner who has spoken with CNN in the past. The inmates raised their voices against the government and demanded more rights.
Guards fired warning shots and tear gas as prisoners chanted anti-government slogans, according to the prisoner, who obtained access to a phone during the incident and spoke with CNN Tuesday.
Guards ordered the prisoners to return to their cells. The inmates refused but dispersed and re-entered their cells after the guards exerted force, the prisoner said.
Tuesday morning, they reassembled in the main hall and resumed their protests, the prisoner said. Again, guards responded with tear gas and bullets fired in the air. Two prisoners were killed and seven were wounded, said the prisoner, who did not want to be identified for fear of reprisal from prison guards.
Protesters in Yemen been demonstrating for weeks, demanding the ouster of Saleh, who has ruled Yemen since 1978.
An Interior Ministry official commented solely on Monday's incident.
"Prisoners were causing chaos and security forces had to do what was necessary to keep matters under control," the official told CNN.
A government statement said the inmates rioted because they wanted pardons. It acknowledged that riot police had subdued the inmates and said it was investigating the incident.
The government said it was beefing up security around Sanaa, the capital, "over terror concerns in the aftermath of multiple terror attacks on security and army personnel."
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.