Egypt unrest: BBC witnesses Cairo raid on pro-Morsi camps
At four o'clock in the morning, at one of the entrances to the Rabaa al-Adawiya mosque encampment, a dozen guards stood behind a row of sandbags.
The men carried sticks and wore small gas masks around their necks. Some leaned back against the sandbags. Beyond the barricade, I could just make out the heads of a group of men standing for pre-dawn prayers. No-one appeared to want to leave.
My colleagues and I then drove round the perimeter of the encampment.
Just before 05:00 (03:00 GMT), the sky started to lighten. We saw police officers putting on black flak jackets and testing out gas masks. Rows of police trucks were parked on side roads. It seemed clear that a raid was about to begin.
At 06:40, from a street corner near the encampment, I saw six police jeeps drive at speed down a main road. Officers carrying weapons jumped out and stopped anyone from going forward.
A few minutes later, a single armoured military bulldozer drove down the same road, towards the encampment. The bulldozer began to push away the piles of bricks and sandbags which marked the entry to pro-Morsi territory. Protesters fought back by throwing stones and burning tyres.
At the same time, riot police in armoured personnel carriers advanced through nearby streets.
For more than two hours I heard the crack of live ammunition. The sharp bangs were accompanied by the bass thuds of exploding tear gas canisters.
For a while it was hard to breathe without a gas mask. Some local residents held handkerchiefs to their faces and watched the police deployment from their balconies.
A small crowd watched a confrontation between police and protesters at a nearby junction.
"They are killing us," said one man, who was a supporter of ousted President Mohammed Morsi.
The man had tears in his eyes and he had to speak quietly. The residents around him all were supporting the security forces.
My colleagues and I then walked closer towards the frontline. We were less than 200m from the encampment. Thick trails of black smoke stopped us from getting a look at what was happening around the mosque. But the wind sometimes blew over the sound of a man's voice on loudspeaker from the mosque area. The words were too difficult to make out.
We then decided to leave. As we drove away, two police officers ran towards our vehicle, cocking their pistols to make us stop. They had orders to confiscate camera footage.
They let us go, and we made our way past an outer cordon run by the military and into the centre of Cairo.
No-one had known the exact timing of the security forces's operation. In recent days, the rumours that govern Cairo had predicted the time on several occasions; each prediction had come to nothing.
But the protesters at the Rabaa mosque knew that, at some point, the government would come for them.