Protesters take to the Presidential Palace in Yemeni capital of Sanaa. (credit John McNab/Flickr)

Yemeni troops opened fire on protestors as petrol bombs set police cars on fire to the chants of "Escalation, escalation," reports Reuters.

The protestors--young men, many believed to be Sanaa University students--were demanding Saleh step down from his position. For months the anti-Saleh groups have been battling Saleh-loyalists as tensions grew. 

From Reuters: 

Saleh, recovering in Saudi Arabia from a June assassination attempt, is holding on to power despite international pressure to quit and eight months of protests against his 33-year rule which have bought the impoverished Arab state to the brink of civil war.

Recent political decisions made by the Yemeni leader brought about the latest uproar by protestors, The Associated Press reported. 

From the Associated Press:

The attack was the deadliest in months against protesters, who have been massing daily in Sanaa and other cities since February to demand Saleh’s removal. The protests have swelled the past week as the movement tries to renergize, angered by Saleh’s latest decision to deputize his president to negotiate a power-transfer deal. Many believe the move is just the latest of many delaying tactics. 

According to witnesses at the scene, shots were fired from atop the Presidential Palace roof by snipers when crowds of protesters began marching toward the guarded building.

Despite calls for his abdication, President Saleh is said to be looking for a "U.S.-backed deal" that ensures immunity from prosecution before a deal can be made for his resignation, reports the Associated Press.