Aleppo: BBC journalist on Syria army moving in on city
We came into the city last night and since first light, we have been hearing the amplification of artillery bombardment.
There have been gunfights in a number of areas and helicopters flying overhead.
We are hearing that there is a government offensive targeting Salah el-Din, which has been one of the most restive neighbourhoods - perhaps the key district - and which has been in the hands of the opposition Free Syrian Army for a number of days now.
We had heard that government troops were massing outside the city, though on this occasion we believe they are coming from an area they control inside Aleppo.
The rebels are saying that they have destroyed a number of tanks. Though this cannot be verified, there is evidence that they have been able to do that - they have rocket-propelled grenades and know how to use them to target these vehicles.
But the truth is they are outgunned and outmanned.
A regular trickle of trucks and cars packed with civilians has been leaving from Salah el-Din and other areas.
They have a few belongings, but not much. They don't appear to have had much time to pack before heading out into the countryside, and safety.
It is almost impossible for us to get into some areas - one has to conclude that it would be equally difficult for residents to get out and some undoubtedly must be trapped.
The atmosphere has changed since we were here three days ago. It is eerily quiet, there are very few residents around and the mood amongst the rebels is very tense.
The commander of one of the largest brigades operating in Aleppo was even deliberating pulling his men out because he was not getting enough ammunition.
He was urged by his men not to leave - they are still here, they have been fighting this morning and wounded fighters have been brought back to the area for treatment in a makeshift clinic.
The rebels may insist in interviews that they will prevail, but the mood on the ground is different.
It is very hard not to conclude that the firepower they face is so overwhelming and Aleppo so important for President Assad's government that resisting will be incredibly difficult, if not impossible.
From the perspective of military tactics, perhaps the rebels decided to strike too soon in Aleppo before they had the kinds of armaments needed to be able to resist the inevtiable counter-offensive.
Having to leave Aleppo would be a setback for the rebels, but they will regroup in the countryside, where they have been skirmishing with the government for months.