A relative calm prevailed late Tuesday after a ceasefire went into effect between Yemeni government forces and opposition protesters in the capital, following three days of violence that killed more than 77 people, the state-run Yemeni television reported.
The truce was negotiated by Vice President Abed Rabbo Mansour Hadi and several foreign envoys, including the US and British ambassadors in Sana'a, dpa reported.
Clashes had intensified earlier Tuesday between forces loyal to Yemeni President Ali Abduallah Saleh and army defectors, leaving at least 12 people killed.
Heavy gunfire and shelling hit the capital Sana'a in what has been described by activists as the fiercest attack yet against peaceful protesters, who since February have been calling for Saleh to step down from his 32-years of rule.
More than 77 people have been killed since Sunday, when government forces began an attack on protesters, activists in Sana'a said.
In Geneva, the United Nations said Tuesday that four children were killed by gunfire during the unrest on Sunday and Monday. Marixie Mercado, a spokeswoman for the UN Children's Fund (UNICEF), also said that 18 minors were wounded.
Tuesday's clashes began in Sana'a after government forces shelled protesters in a sit-in, leaving at least nine dead.
One person was killed later after a shell hit al-Iman University in Sana'a.
In the flashpoint city of Taiz, protesters staged a march that ended at the provincial council building.
Government forces used heavy artillery and machine guns against protesters and residential areas in the southern city over night, leaving one person dead, activists said.
Another person was reportedly killed in clashes with gunmen.
Enraged with the fresh repression of protests, demonstrators organized marches Tuesday in six Yemeni provinces denouncing the killings by Saleh forces and the regional and international silence.
Protesters vowed to step up the uprising, chanting slogans such as "we will not retreat" and "we will topple the regime at whatever cost."
Members of the Arab Parliament, which is made up of 88 members from different Arab countries, recommended on Tuesday freezing the Yemeni membership until stability returns to the country.
This has been one of the fiercest crackdown against pro-democracy demonstrators since protests began last February calling for Saleh to step down. He is currently recuperating in Saudi Arabia.
Yemen has been in a political stalemate for months after Saleh refused to sign the Gulf initiative three times. Saleh recently assigned deputy vice president Abdu Rabu Mansour Hadi to negotiate with the opposition and sign the Gulf settlement deal on his behalf.
Saleh, who has been recovering in Saudi Arabia's capital Riyadh from injuries sustained in an attack on his presidential palace last month, has resisted calls to step down.