SANAA - At least ten students were injured late on Monday when Yemeni police forces opened fire to break up students' anti-government protest inside the campus of Al-Hodayda University in the Red Sea Al-Hodayda province, witnesses said.

Witnesses said the police forces stormed the campus, shooting and injuring at least 10 students. Local doctors said two of the injured were in critical conditions.

The students demanded the postponement of study in the university "until the regime of President Ali Abdullah Saleh falls," the witnesses said.

Meanwhile, death toll from clashes between police and a rally of teachers and students on Monday in southern Taiz province rose to four after one injured died of his shot wound, according to local medics.

On Sunday, the opposition gave President Saleh two days to sign the Gulf-brokered initiative for power transition, otherwise it would leave Saleh to face "the people's choice."

Protesters vowed to escalate their peaceful protests through marching forward all government ministries and presidential palaces in major cites to force Saleh's immediate ouster.

Yemen's security situation has been aggravated by the ongoing street protests that rocked major provinces of the impoverished country to repeat demand of an immediate end to the 33-year rule of Saleh.