Another explosion. This time, churning white smoke belches up to my left. Within seconds it rises hundreds of feet and joins the shroud of black smoke to form a huge arch, hanging over the south of Damascus, blocking out the hills beyond.
Once, residents of Damascus believed the fighting would never come their way. Now, there is no-one here who cannot see, and hear, the vicious bombardment of the capital's suburbs.
I can't tell whether the latest smoke came from an artillery attack, from mortars or from warplanes. I heard no planes but it's known they have been used to attack areas where rebels are based. I can't tell who died in the attacks because as we got close we were immediately picked up and detained by Syrian troops.
They were initially very angry, yelling and finger pointing, guns at the ready. They wanted to see our cameras and what we had shot. Nothing they do must be seen.
The world cannot know how they are clearing the rebellious suburbs of the capital.
After being passed up the chain of command, a General finally released us, with the usual "welcome, welcome" and an armed escort far away from the fighting. But nowhere is very far away. We stop again by an army checkpoint. There is a massive explosion perhaps five hundred meters away. Another mushroom of white smoke billows up into the murky sky.
Syria's state media reports clashes with "an armed terrorist group". The army, they say, have "eliminated a number of its members". A Syrian human rights organisation reports a daily death toll of 160, including 67 in Damascus and its suburbs, mainly from shelling.
The killing is more frequent than ever. Amnesty International blames the indiscriminate use of air power; jets, helicopters, artillery and mortars for a death toll that exceeded five thousand last month alone. Five thousand in one month, four thousand of them civilians.
As we drove to the opposite side of Damascus from the arch of smoke, I saw areas I had last visited two months ago.
They have since been bombarded and in some cases bulldozed. A mosque by the main road has huge gaping holes in its dome, bullet holes in its minaret. Blocks of flats have chunks taken from them by tank or artillery shells. Houses have been demolished. We are told this was to give soldiers a line of sight to their targets and to prevent rebels using the buildings as firing points.
And everywhere we drive there are tanks. Usually two or three Russian made tanks together, turrets facing different directions; a threat from every angle.
Damascus has deteriorated. The war has come, not to its doorstep as it had when I was last here in July, but to its front room. Even President Assad can see it now, if he looks out of the windows of his home; to the left or to the right and in an arc across his once-lovely capital.