At dawn on Wednesday morning, protesters opposed to the military regime were attacked by unidentified armed men outside of Egypt’s ministry of defence in Cairo. At least 20 people were killed. Our Observer, who was on the scene, raised questions about the identity of the assailants, who he says were very well-armed.
The incident comes just a few weeks ahead of Egypt's first presidential election since Hosni Mubarak’s fall. Three candidates – Mohammed Morsi, of the Muslim Brotherhood, the Islamist Abdel Moneim Aboul Foutouh, and the left-wing lawyer Khaled Ali – have decided to halt their campaigning due to the violence.
The attackers throwing Molotov cocktails. 

“They attacked protesters with tear gas”

Mohamed Salah (@MhmdSalah1 on Twitter), a 25-year-old Egyptian blogger, was outside the ministry of defence during the attacks.
I had been there since 7 p.m. Tuesday night. Approximately 2,000 peaceful protesters were gathered in front of the ministry. They were all yelling “down with the military regime,” and demanding an immediate transition to a civilian government. I noted there were people from many different sides: there were liberals, Salafists, youths from the April 6 movement (LINK)… [According to other witnesses, the majority of protesters were supporters of Salafist politician Abou Ismail, who was disqualified from the presidential race by Egypt’s electoral committee]. Four armoured vehicles were stationed nearby. Interestingly, they did not budge during the attack.
“I saw five men fall to the ground, struck by bullets. One was a friend of mine”
At 1 a.m., about 100 “baltagiyas” [name given to the government’s henchmen under Hosni Mubarak’s reign] attacked the protesters with tear gas and with live bullets [on Twitter, there is much discussion among Egyptians about how civilians got their hands on tear gas, as it is usually wielded only by security forces]. Some had been lurking around the protesters for a while; others joined in for the attack. They were all dressed in civilian clothing, so they were not “officially” soldiers, but they were incredibly well armed [other witnesses also spoke of metal bars and clubs.] Meanwhile, the protesters that I saw were unarmed. All they did was throw rocks. [According to Egypt’s security forces, both sides threw Molotov cocktails.]
During the attack, I saw five men fall to the ground just a few feet away from me. They had been struck by bullets. One was a friend of mine. His name was Talaat, he was 20 years old and studied at Ain Shams University. The wounded were immediately taken to field hospitals set up nearby.
Video of the clashes that took place early Tuesday morning. 
Photo posted on Twitter by @3mo_shehab.
A motorcyclist covered in blood after transporting the wounded to the hospital. Photo posted on Yfrog by Ruwaydah Mostafa.
A shell found at the scene of the attacks. Photo taken by our Observer Mohamed Salah.
Blood at the scene of the attacks Photo taken by our Observer Mohamed Salah.