I am travelling with a group of rebel fighters who call themselves the Free Syrian Army.
They heard at about 03:00 that there had been a large bombardment of areas of Homs that are opposed to the regime.
As we came into the city this afternoon we heard a lot of heavy machine-gun fire and there were a lot of unexplained explosions.
Parts of the city which oppose the regime are now virtually cut off, so we had to travel using a very elaborate route, escorted by activists who were bringing medical supplies and fresh blood donated a few hours earlier by people in the villages around Homs.
The Syrian government says that claims of a massacre are fabricated and that the bodies are of people kidnapped by rebel fighters. The opposition said it was a massacre.
In the part of Homs where I am people treat the government view with absolute scorn. They say they have been digging bodies out of the rubble, and that they were assaulted with tanks, heavy machine guns, mortars: heavy weapons of a type that only the government possesses.
The Free Syrian Army did use some of its weapons in reply to that but it has only light weapons. It says that these deaths can only be attributed to the government.
There were very inflated claims for the numbers of deaths in last night's assault at the beginning - figures of 200 and even higher were being discussed. But now independent and reputable human rights groups are talking about a death toll in the region of 55.
However people in the worst affected suburb, Khalidiya, were describing digging 100 bodies out of the rubble, so the true figure may be somewhere in between.
Across Syria a picture is emerging of government forces holding the centre of big towns and the main roads, and the Free Syrian Army becoming increasingly active and almost controlling parts of cities like Homs and areas of the countryside.
These men have only very light weapons - machine-guns and rocket propelled grenades - and they have no answer when government forces decide to use heavy weapons, as they appear to have done overnight.
It is a very, very bad day for Syria if the numbers are anything like even the lowest estimate.
Once the death toll is established, who is responsible becomes the question.
Already there are completely different accounts from the Syrian government and the Syrian opposition.
Why did this take place on the day the UN Security Council was voting on a motion critic of Syria?
It could be because the Free Syrian Army have been so successful that areas of Homs have slipped from the government's grasp. I think the government army commanders on the ground simply thought they could not wait any longer.
The Free Syrian Army told me this morning that they were going to conduct what they call a "general offensive" in reply to what has happened in Homs.
I think we are going to see an escalation in the violence. We are seeing bigger and bigger attacks by the Free Syrian Army.
On Friday we followed an attack on an army base outside Homs. The fighters said they had over 100 men - I counted at least 60. They did not manage to take that base but they attacked over a number of hours and it was a big battle.
I think the focus in Syria now is moving away from street protests - though they still continue - and into an escalating guerrilla campaign.