Up to 95 people are feared dead after security forces backed by bulldozers moved in on two huge protest camps set up in Cairo by supporters of Egypt's ousted president Mohammed Morsi.
Video: Dozens killed as Egyptian security forces disperse protesters (Lateline)
Video: Raw footage of the bloodshed in Cairo (Warning: contains graphic images) (ABC News)
Photo: Smoke rises as the military moves in on a crowd of protesters in Cairo. (Reuters TV)
The violence has led to widespread condemnation of the Egyptian military's actions from many world figures, including United Nations secretary-general Ban Ki-Moon, as the Egyptian government declared a state of emergency.
The operation began shortly after dawn on Wednesday when security forces surrounded the sprawling Rabaa al-Adawiya camp in east Cairo and a similar one at Nahda Square, in the centre of the capital.
While reports of the number of dead vary wildly, the country's health ministry said 95 people had been killed and 874 injured.
"The dead are both from police and civilians," the ministry's spokesman, Hamdi Abdel Karim, said.
"We are waiting to get more details."
A TV cameraman for Britain's Sky News, who was covering the clashes, was among those shot and killed, the channel said.
Mick Deane, a 62-year-old father of two children, had worked for Sky for 15 years and had been based in Washington DC and Jerusalem.
Six members of the Egyptian security forces were killed, state TV reported, quoting the government's interior ministry.
The state-run Nile TV said a further 66 members of the security forces had been wounded.
A Reuters reporter said he had seen about 20 people shot in the legs by soldiers, after Mr Morsi's supporters threw stones and petrol bombs at the Egyptian troops.
The Muslim Brotherhood urged Egyptians to take to the streets in their thousands to denounce the "massacre".
"This is not an attempt to disperse, but a bloody attempt to crush all voices of opposition to the military coup," Brotherhood spokesman Gehad al-Haddad said
General Abdel Fattah Othman, a senior interior ministry official, told local TV a number of leaders of the Muslim Brotherhood had been arrested.
"We have arrested a number of Brotherhood leaders but it's too early to announce their names," he said.
Meanwhile, state news agencies are reporting 17 people were killed in the province of Fayoum, south of Cairo, following clashes at a police station.
Clashes rage as security forces move in
Photo: Muslim Brotherhood supporters run from tear gas fired by Egyptian police in Cairo. (AFP: Khaled Desouki)
Intense clashes raged on one side of the Rabaa camp as automatic fire was heard. It was not immediately clear who was doing the shooting.
"It is nasty inside, they are destroying our tents. We can't breathe inside and many people are in hospital," Murad Ahmed, who was at the Rabaa camp, said.
Security forces surrounded the camp early in the morning and fired tear gas as they began moving in on the thousands of pro-Morsi protesters who have defied ultimatums to end their protests.
Canisters of tear gas rained down on tents set up by the protesters at one end of the camp, sparking pandemonium that saw protesters running in all directions.
Men in gas masks rushed to grab each canister and throw them in small containers of water, as the main stage near the mosque of the protest camp blared Islamic anthems and protesters chanted "Allahu Akbar" (God is greatest).
"Tear gas was falling from the sky like rain. There are no ambulances inside. They closed every entrance," protester Khaled Ahmed, 20, a university student wearing a hard hat with tears streaming down his face, said.
"There are women and children in there. God help them. This is a siege, a military attack on a civilian protest camp."
Churches torched in reprisal attacks across central Egypt
Mr Morsi's supporters torched three churches in reprisal attacks across central Egypt after police moved on the camps in Cairo.
Assailants threw firebombs at Mar Gergiss church in Sohag, a city with a large community of Coptic Christians, causing it to burn down, the official MENA news agency said.
Video: Freelance journalist Rebecca Collard discusses the latest situation in Cairo. (Lateline)
Security officials told AFP that another two churches were attacked in El-Menia province, leaving them partially damaged by fire.
Coptic rights group the Maspero Youth Union reported the same information, accusing the Muslim Brotherhood movement of "waging a war of retaliation" against the country's Christians.
The Coptic church backed Mr Morsi's removal, with Patriarch Tawadros II appearing alongside army chief General Abdel Fattah al-Sisi as he announced the military coup on July 3.
Trains stopped in bid to stop new protest camps forming
Authorities had stopped all train services in and out of Cairo to prevent Mr Morsi's supporters from reassembling after the camps were dispersed.
"Train services in and out of Cairo in all directions have been stopped until further notice... for security reasons and to prevent people from mobilising," the railway authority said.
The interior ministry said police had finished breaking up the smaller Nahda Square protest camp, on the other side of Cairo from Rabaa.
Nahda Square was "totally under control" and "police forces have managed to remove most of the tents in the square," the ministry said.
More than 300 people have already died in political violence since the army overthrew Mr Morsi on July 3, including dozens of his supporters killed by security forces in two separate earlier incidents.
Violent clashes spark protest in Sydney suburb
The reports from Egypt have sparked a spontaneous protest in south-west Sydney by Australian Egyptians.
Mohammed Hilal says about 300 people have gathered outside Lakemba railway station to demand international condemnation of what he described as a massacre.
"We are gathering here, a few hundred people, in front of Lakemba station demonstrating, condemning the massacres, the hundred and hundreds of people being killed now in Egypt," he said.
"It just happened because when we heard the news in Egypt (we) could not really standby.
"I'm sure every honest Egyptian and every honest human being that feels the humanity, that feels for everyone, that (wants) to be free in this world, will come out and condemn this massacre in Egypt."
