I received the following message from Syria:

A live Massacre unfolds in the Saydnaya prison in Syria
The regime denies, and the world is silent

UPDATE ONE:
The event was reportedly instigated on July 4th, by the attitude of the prison guards, who during an unannounced search of prison cells, where Islamist prisoners are held, desecrated copies of the Qur’an. This led to a shoving match that soon developed into a full-scale riot when guards opened fire on prisoners and killed nine of them. Rather than getting cowed, the prisoners were up in arms about this, and the in the ensuing melee, more prisoners were killed, bringing the total to 25, but the prisoners got the upper-hand taking the warden of the prisoner and 8 of his top officers as hostages. This led to the surrender of many of the guards, bringing the total number of hostages to 300-400.
(The total number of prisoners in Saydnaya prison is variedly estimated at 3000-5000, most of which are political prisoners of various backgrounds, including Islamist of various trends, communists, liberals and Kurdish activists).
The remaining “free” officers used tear gas and drove the prisoners and their hostages to the roof of the prison, where one of some prisoners used cellular phones confiscated from the guards to get in touch with their human rights activists, news agencies and their parents. This is how we continue to get our information at this stage, albeit direct contact with the prisoners came to a halt at 3 pm on July 5th when the authorities shut down the local cellular service. After that, the main source of information became the parents and bystanders who traveled back forth between the prison site and the Tishreen Military Hospital in Damascus where the dead and wounded are being taken.
Before the interruption of direct communications, the prisoners managed to provide the details above in addition to the following points:
1) Prisoners have up until that point refrained from sing any of the confiscated weapons as a gesture of good will.
2) They have appointed one of their ranks to negotiate with the authorities, Yassir Bahr.
3) Their only demand was they will not be killed as a result of this development.
4) The authorities refused to make any promises and said that first, the prisoners should surrender, before discussions could take place, and threatened to storm the prison even if this lead to a 1,000 deaths.
5) When the prisoners refused to surrender, the authorities beat and arrested the main negotiator, Yasser.
6) By 3 pm, more than 30 tanks were surrounding the prison, as we as a number of armored divisions.
7) Rumors that the prison was bombed from the air spread among the local population, but they are known to be false, at least this was the case up until 3 pm.
8 ) Parents of inmates are gathered at a safe distance from prison.
This is where the situation stood at 3:00 pm, July 5th.
The Associated Press, BBC, Human Rights Watch, Al-Jazeerah, Al-Arabiyah and the Lebanese station New TV picked up on the event (in fact both the BBC and New TV spoke directly to one of the inmates who using a confiscated cell phone), the German government expressed concerns, and on the morning of July 6th, the Syrian Arab News Agency downplayed the event, describing as it as a riot instigated by imprisoned terrorist groups, and claiming that the situation was now under control.
It is not, as the next update will show.

UPDATE TWO:
* As of the morning of July 6, the prisoners are still holding their grounds on the roof of the prison, while government troops seem to be trying to shoot their way in.
* As a sign of good will, the prisoners have reportedly abandoned most confiscated weapons.
* Prisoners still hold many hostages including the warden and his top officers.
* More reinforcements were sent to the prison on the morn of July 6th.
* Ambulances continue to go back and forth between the prison and Tishreen hospital.
* Parents who went to Tishreen hospital were denied access. A crowd of over 200 parents is now surrounding the hospital. A scuffle with the authorities took place in the evening, security officers reportedly used force wounding many, blood can be seen on the ground in many locations around the entrance of the hospital.
* Mothers of the inmates who came to the prison site offered to negotiate with their sons and talk them into surrendering themselves, the authorities refused. As a result mothers tried to block access to the prison by camping on the road, security officers intervened, leading to a number of wounded.
The situation continues to unfold, despite official denials. Observers confirm this. The death toll will likely rise to several hundreds after all is done.