Syrian security forces fired on anti-government demonstrations across the country today, killing at least 24 people - including several children, activists said.
Some of the worst violence was reported in Homs, a city in central Syria that has emerged as the epicentre of the revolt against President Bashar Assad.
"The earth was shaking," a Homs resident told The Associated Press by telephone, saying explosions and cracks of gunfire erupted in the early morning.
"Armoured personnel carriers drove through the streets and opened fire randomly with heavy machine guns."
Despite the relentless bloodshed, Mr Assad has refused to buckle to the pressure to step down and has shown no signs of easing his crackdown.
The United Nations estimates more than 4,000 people have been killed in the military assault on dissent since March.
Two boys, aged 10 and 12, were hit by stray bullets near government checkpoints in Homs, according to activists. At least two other young teenagers were killed elsewhere.
Rami Abdul-Rahman, the head of the British-based Syrian Observatory for Human Rights, said the 10-year-old was shot as he crossed the street in the Bab Sbaaa neighbourhood. The 12-year-old was struck as he walked in a crowd exiting a mosque.
Anti-government demonstrations traditionally peak after Friday's midday prayers, although witnesses say there appeared to be a concerted effort to prevent any gatherings this week. Troops were deployed heavily and, in many cases, locked down areas before prayers even began.
Security forces also reportedly fired on protests in the Damascus suburbs, the eastern city of Deir el-Zour, Idlbi province near Turkey and elsewhere.
In the southern town of Daraa, activists said telephone and internet lines were cut.
An activist coalition called the Local Co-ordinating Committees said up to 35 were killed today, most of them in Homs. The Britain-based Observatory had a death count of 24.
Assad is under growing international pressure to curb the bloodshed.
Turkey, the Arab League and the European Union have imposed sanctions aimed at squeezing the ailing economy.
Today, Turkey urged Assad to punish his security forces and accept an Arab League observer mission if he is "sincere" in his repudiation of violence against civilians.
Turkey, meanwhile, moved to suspend a 2008 free trade agreement with Syria, which will lead to the imposition of taxes of up to 30% on some Syrian goods.