Syrian troops opened fire at a group of protesters in Damascus Monday night injuring four, the Guardian reported.

Activist Abu Abdallah, from the Guardian:

Protestors in Damascus in 2011 (Creative Commons)

"There were hundreds of demonstrators at the main square of Hajar al-Aswad, and suddenly buses of security police and shabbiha [pro-Assad militia] turned up and started firing into the crowd."

Prior to the shooting, crowds were marching carrying signs in support of the city of Homs, which has come under attack by Syrian forces.

Homs was reportedly shelled by Syrian tanks Monday night.

U.S. Senator John McCain, on a visit to Egypt, said Washington needs to help arm and equip Syrian rebels.

McCain, from the Daily Telegraph:

"The massacre in Syria goes on... It is time we gave them the wherewithal to fight back and stop the slaughter."