Yemeni President Ali Abdullah Saleh announced a state of emergency on Friday after medics said 46 people were killed when pro-regime loyalists and police opened fire on protesters in Sanaa.
"The national security council announces a state of emergency across Yemen," Saleh told reporters. The state of emergency will bar citizens from carrying weapons.
More than 46 anti-regime protesters were shot dead and over 300 wounded during a demonstration in the Yemeni capital Sanaa on Friday, witnesses and medics said as the opposition said that there was no more mutual understanding with the government.
Witnesses said pro-Saleh "thugs" opened fire on protesters from rooftops near the square at Sanaa University, where demonstrators calling for the fall of the president have been encamped since Feb. 21.
"The police were not present and did not open fire. The clashes happened between citizens and demonstrators," he told a news conference. "It is clear there are armed elements among the demonstrators."
An AFP correspondent later saw police firing at protesters as well.
Medics said that at least 41 people were killed and scores more wounded in the bloodbath.
Yemen's interior minister said 25 people had been shot dead at Friday's anti-government protest, far fewer than the 41 people doctors said had been killed.
Minister Muttahar al-Masri also said a curfew and other measures to prevent a further deterioration in the situation in Yemen were still being discussed.
"Most of the wounds were to the head, neck and chest," one medic said.
Yemen's tourism minister resigned from his post and quit the ruling party on Friday after the shooting attack on anti-government protesters in Sanaa, becoming the first cabinet member to defect in the crisis.
"I did it today. I resigned from government and the People's General Congress," Minister Nabil Hasan al-Faqih told Reuters, saying the decision was a result of "the events the country is going through".
No mutual understanding
Yemen's opposition said there was no longer any way to reach a mutual understanding with the government after dozens of people were killed when security men and snipers fired into a protest.
"We condemn these crimes," said Yassin Noman, rotating president of Yemen's umbrella opposition group, asking President Ali Abdullah Saleh to step aside.
"There is no longer any possibility of mutual understanding with this regime and he has no choice but to surrender authority to the people."
Earlier, thousands of people have camped out in the square since Feb. 21, demanding the departure of Saleh, who has been in power since 1978.
The Friday bloodbath came after five Yemeni protesters were wounded in an attack on Wednesday night by masked men on the Sanaa University sit-in.
Anti-government activists told AFP that the attackers wielding guns, clubs and daggers were "thugs" loyal to the regime.
Witnesses said that dozens of people were injured when police and loyalists of the ruling General People's Congress party attacked protesters in the square with live rounds and tear gas on Sunday.
Protest after prayer
Gunfire broke out when security forces tried to prevent anti-government worshippers from marching after prayers near the protest base at the Sanaa University, and plumes of smoke from burning tires filled the air.
Yemen, next door to top oil exporter Saudi Arabia, has been rocked by weeks of demonstrations that have undermined Saleh's grip on power. Tens of thousands of protesters were also gathered in cities across Yemen, from the southern port city of Aden to Hodeida in the west.
The United States, which has long seen Saleh as a bulwark against a dynamic al Qaeda wing based in Yemen, has condemned the bloodshed and backed the right for peaceful protest, but has insisted only dialogue can end the political crisis.
Saleh has promised to step down in 2013 and offered a new constitution giving more powers to parliament, but he has refused his critics' main demand to quit immediately.
A string of Saleh's allies have recently defected to the protesters, who are frustrated by rampant corruption and soaring unemployment. Some 40 percent of the population live on $2 a day or less in Yemen, and a third face chronic hunger.