Speaking to Al Jazeera, Gehad Haddad, a spokesman for Muslim Brotherhood, said that at around 3.30 in the morning, army and police forces started firing at sit-in protesters in front of the Republican Guard headquarters in Cairo.
“We have people hit in the head, we have bullets that exploded as they entered the body, cluttering organs and body parts” said Haddad.
“Every police force in the world understands how to disperse a sit-in. This is just a criminal activity targeting protesters.”
However, the military said a "terrorist group"was responsible, adding that two officer had also been killed.
An Al Jazeera correspondent said military checkpoints had been deployed around Nasr City.
The Muslim Brotherhood's Haddad said there were two things “the bloodbath” was trying to do.
“First is that we leave streets and forego the objective of bringing democracy in Egypt after 60 sixty years of military tyranny or they think that our blood is cheaper than any other’s blood in Egypt and no one would care,” he said.
“We are sticking to our ground, we will not be brought into a cycle of violence, we know how deadly that would be. Even if that means we will have to become the punching bag of the rest of society and our blood will flow for the rest of Egyptians to wake up and the rest of the world to understand that we are adamants of bringing democracy to our country.”
The military has also shut down the Cairo headquarters of the Muslim Brotherhood, saying weapons were found inside it. Egyptian state TV reports that some of the 200 supporters of Morsi arrested earlier on Monday have been released.