Syrian forces killed 20 civilians on Thursday in the flashpoint central city or Homs, a day after Damascus agreed to an Arab League peace deal to end the bloodshed, a rights watchdog said. \"Twenty civilians were killed today in several neighbourhoods of Homs where the sound of gunfire can still be heard,\" said the Syrian Observatory for Human Rights in a statement received by AFP. The Observatory earlier reported nine dead in Homs, where Syrian forces reportedly used tank-mounted heavy machineguns a day after Damascus pledged to withdraw its troops from protest hubs under a deal to end months of bloodshed.