Thousands of protesters hit the streets in cities across Syria on Friday, billed as a "day of martyrdom", to demand political reforms.
However, witnesses said gunmen in plainclothes attacked one of the protest rallies in Douma, a suburb of the capital Damascus, firing live ammunition and killing at least four people.
The Syrian state news agency accused "armed gangs" for the firing, while the government ordered an inquiry into the incident.
Al Jazeera's Cal Perry reports from Damascus.
Source: Al Jazeera