BEIRUT — Syrian security forces killed at least eight people today, including a 16-year-old boy, as thousands of people poured into the streets across the country calling for the downfall of President Bashar Assad’s autocratic regime, activists said.

The protests came hours after Syrian troops backed by tanks and helicopter gunships seized control earlier today of another northwestern town in the latest military operation to quell the dissent.

Since the protests erupted in mid-March, Assad has unleashed the military to crush street demonstrations. Human rights activists say more than 1,400 Syrians have been killed and 10,000 detained.

“What is our guilt? We just demanded freedom and democracy nothing else,” said Mohamed, who asked to be identified only by his first name, at a refugee camp in neighboring Turkey. He and other refugees offered fresh accounts of summary executions used to suppress the pro-democracy movement.

“I saw people who were beheaded with machine-gun fire from helicopters,” and a man tortured to death when security forces “poured acid on to his body,” he said.

Mohamed fled with his family as the military besieged Jisr al-Shughour, a rebellious town the government recaptured last Sunday.