A mass grave containing dead bodies of 25 persons was discovered in the Damascus district of Al-Qadam, the state-run Syrian Arab News Agency (SANA) reported on Friday.  SANA said personnel, upon information provided by civilians, located the mass grave with the 25 corpses in it.  The official news agency said the slain persons had BEEN blindfolded and handcufffed, and charged opposition armed groups had taken them as hostages before killing them.  Syria has witnessed such horrific scenes since flare-up of the rebellion against the regime more than 18 months ago.  Scores of people have been killed in cold blood, as well as in street fighting. Unofficial figures indicate that some 25,000 may have lost their lives so far.