A badly wounded protester is helped away after the Abbasiya Square attack in Cairo  (Twitter)

Armed assailants have killed at least six people who had been camping out near the Egyptian Defence Ministry in Cairo's Abbasiya Square to protest against the disqualification of Salafi leader Hazem Salah Abu-Ismail from May's presidential race.

According to witnesses, the thugs attacked the camp with cement-based bombs, stones, Molotov cocktails, birdshot and teargas canisters.

"Too much blood here. Some people are breaking down in tears. This is just like December. #MOD," tweeted Ahmad Aggour, referring to the deaths at the Occupy Cabinet protest in in Egypt in December.

The health minister confirmed that six people had been killed by birdshot pellets. Officials told AP that at least 50 protesters were wounded.

But the death toll could be higher, according to activists. "Some report 11 killed today in Abbasiya clashes. 2 confirmed dead by field hospital doctors so far and 24 birdshot injuries (4 in eye). #MOD," tweeted photojournalist Jonathan Rashad. His claim was confirmed by independent doctors.

Other activists reported clashes in Abbasiya Square between protesters and thugs outside the subway station.

Protesters reportedly hit back with stones and set up a second field hospital to treat the wounded.

Meanwhile, a group of residents in the area are preparing to march from Fath mosque in Ramses Square to the nearby police station to urge the authorities to intervene in order to protect the peaceful protesters.

"This has to be one of the worst nights of my life. I will inspect myself. #Abbasiya #MOD" tweeted Egyptian journalist Menna.

The Twitter account Tahrir Supplies is coordinating first aid efforts and urging people to stay away from the area. "The situation in Abbasiya is critical, head there if you want to help the injured otherwise we advice you to stay away for your own safety," it said.

Abu-Ismail was thrown out of the presidential race because his mother held dual Egyptian-US citizenship in violation of eligibility rules.

"[The sit-in] initially started off as one that was called for by the angry supporters of Abu Ismail, who was disqualified from the race; people gathered there to protest his disqualification," Al Jazeera's Rawya Rageh said.

"But as with most protests over the past few months, it escalated into something bigger into a protest against the overall military practices and the way the ruling military council has been running the country over the past 14 months."