BEIRUT, Lebanon — Syrian security forces fired their weapons into crowds of mourners in at least three towns on Saturday as tens of thousands of people buried protesters who were killed a day earlier in the worst bloodshed since the uprising began last month. Human rights activists and witnesses said at least 11 people were killed on Saturday.

The death toll from the protests on Friday, one of the bloodiest days in the so-called Arab Spring, had risen by Saturday to 109 people, a number that activists said was likely to rise as more bodies were returned to their families. Another group said 114 people had been killed.

The bloodshed on Saturday followed a pattern seen frequently in the tumult that has swept the Arab world. Funerals have often turned to demonstrations, where more have been killed by security forces bent on crushing dissent against authoritarian leaders. While Saturday’s death toll paled in comparison with the number killed on Friday, it suggested that the country might be entering a prolonged period of turmoil as protesters continue to press the greatest challenge to the Assad family’s four decades of rule.