This post is part of our special coverage Yemen Protests 2011.

Yemeni forces once again attacked non-violent protesters in front of Sanaa University Friday, March 18, as snipers and soldiers on-the-ground fired live weapons into the crowd, killing an estimated 40 people and wounding another 200.

It was the worst day of violence in the nearly two-month-long protest to oust long-serving president Ali Abdullah Saleh. The high number of casualties more than doubled the previous death count of 29 since protests began in early February. Young Protesters and older opposition party members have been calling on Saleh to step down because they feel his regime is corrupt, stifles the economy and he is responsible for a multitude of human rights abuses in the name of national security.

Fridays always bring out large crowds to anti-Saleh events, and eyewitnesses told journalists that shooters were placed on building roofs and in close-by houses to fire at the crowd as prayers ended. Amnesty International and news organizations called the attacks deliberate and planned. Al Jazeera English quoted its reporters who said many of the casualties were killed by bullet wounds to the head.

Here is a Twitter account of what at least one blogger is dubbing the “Friday Massacre in Sanaa.”

@womanfromyemen: #saleh is taking advantage of whats happening in japan & libya by killing peaceful protesters while no one is watching plz R, #yemen #yf

@shephardm: Horrific scene unfolding in #Yemen. Early reports say firing from nearby roofs of buildings into crowd of student demonstrators. #Sanaa. #yf

@JNovak_Yemen: Friday Massacre in #Sanaa, #Yemen: updates & links at Armies of Liberation: http://bit.ly/dUcltK #YF

@NoonArabia: Almost 50 killed and more than 300 wounded in #Sana'a so far #Yemen #yf

@imothana: Yemen Post editor tells AJE the massacre is ‘on a scale unseen in #Sanaa in decades’ #Yemen #yf

@imothana: AJE reporter: “I can't find any way of describing what happened other than a pre-planned massacre”More than 30 dead & 200 wounded #Yemen #yf

@AnTiCaRioGeNiC: young yemeni Journo,Gamal Sharbi, shot dead during covering the clashes :”( #yf #yemen #feb3

@ionacraig: The sustained gunfire I experienced came from buildings over looking the protest area #yemen #yf

@Abe_Alansy: URGENT : Security forces are trying to intrusions on Rabat St. and shooting sound all over the place. #Yemen #Sanaa #Yf

@ArabsUnite: Another PIC of a martyr today in #sanaa..Ya Rab Er7moo #YF #YEMEN http://twitpic.com/4anjk3

@Nefermaat: tanks and military personnal heading to square where protesters are in #Taez #Yemen… new attack there too ?? #yf May Allah help us !!

@ArabsUnite: Just got off the phone to my 2mum who is in #Yemen,In tears; saying NEVER has she seen PPL killed so ruthlessly & she's only watching TV #YF

@AnTiCaRioGeNiC: revolutionaries at #taiz city shouldn't stay still, they shall start marching toward the republican palace in #taiz #yemen #yf

@alnitak250: #Taiz practically under siege by Saleh forces. Helicopters over the city. #Yemen #yf

@yemen: Arresting a thug was hiding in one of the buildings Change Square #yemen #yf #Sanaa

@YemenFreeVoice: @yemen4change we urge the #UN to impose all necessary measures to protect civilians from #Saleh Mafias #yemen #yf

@yemen4change: We urge the #UN to act immediately on the situation in #Yemen before it's too late! #yf

@ArabsUnite: PLZ spread the word on what's happening, When need be we were..Tunisians, Egyptians, Libyans, Bahraini.. today let's be Yemeni #YF

@al3ini: #AliSaleh precipitated his departure and he has to leave immediately #Yemen #YF #egypt #libya

Warning: Extremely Graphic. Here is a video, uploaded by uthemoon4, showing the dead and wounded in a makeshift hospital near Sanaa University. Here is some very graphic photos of injured protesters.

State of Emergency
Saleh spoke a few hours after the shooting subsided, denying government involvement. He blamed the deaths on “armed elements” at the university square and expressed sorrow for the casulties. He also declared a state of emergency throughout the country, imposing a curfew and outlawing carrying guns.

One of Saleh's largest backers, the United States, condemend the violence and “call[ed] on President Saleh to adhere to his public pledge to allow demonstrations to take place peacefully.”

This, too, brought strong condemnation.

@HarunAlAmriki: He only bankrolled it. RT @blakehounshell: Obama statement just now: “I strongly condemn the violence that has taken place in Yemen today.”

@jeremyscahill: As you watch slaughter in #Yemen, remember the Obama administration significantly increased military aid to its gov't

@haroonmihtar: Shame on president obama for not intervening in #yemen an “ally” of america. Saleh has lost complete legitimacy as president of #yemen

@cbl2: stunning but predictable hypocrisy from Obama in the face of atrocities in #Bahrain and #Yemen