As SNIPERS hidden on rooftops fired on Yemeni protesters yesterday, police sealed off a key escape route with burning tyres, turning the largest of a month of anti-government demonstrations into a killing field in which at least 46 people - including several children - died.
The escalation in President Ali Abdullah Saleh's crackdown suggested he was growing more fearful that the unprecedented street protests set off by the region's unrest could unravel his 32-year grip on power.
The United States - which supports Mr Saleh's government with hundreds of millions of dollars in military aid to battle one of al-Qaeda's most active franchises - condemned the violence. President Barack Obama said those responsible must be held accountable, and that Mr Saleh should honour his vow to allow peaceful demonstrations.
Instead, Mr Saleh declared a nationwide state of emergency that formally gave his security forces a freer hand to confront demonstrators.
The protest in the capital, Sanaa, drew tens of thousands of people, the largest crowd yet in the popular uprising that first gathered pace a day after Hosni Mubarak was toppled in Egypt. Yemenis are demanding Mr Saleh is ousted, rejecting offers to discuss a unity government.
A military helicopter flew low over the area as protesters were arriving after Friday prayers.
Shortly after, gunfire rang out from rooftops and houses, sending the crowd into a panic as dozens of people were hit. Police used burning tyres and petrol to make a wall of fire that blocked demonstrators from fleeing down a main road leading to locations deemed sensitive, including the president's residence.
"It is a massacre," said Mohammad al-Sabri, an opposition spokesman. "This is part of a criminal plan to kill off the protesters, and the president and his relatives are responsible for the bloodshed."
Enraged protesters stormed buildings where the snipers had taken position, dragging out ten people, including paid thugs, who they said would be handed over to judicial authorities.
Witnesses said the snipers wore the beige uniforms of Yemen's elite forces and that others were plainclothes security officers. Mr Saleh denied government forces were involved.
The bloodshed failed to dislodge the protesters, who remained in the square, hurling stones at security troops.
Gregory Johnsen, an expert on Yemen at Princeton University, said: "(Saleh] has been in power for more than three decades and he's falling back on what he knows best, which is increasingly violent methods."(But] Yemen does not have a population that's easily cowed … It's a heavily armed country, many of the people are quite confident and capable of putting security into their own hands."