Syrian government troops backed by tanks attacked three central towns Sunday in an attempt to stop round-the-clock protests there against President Bashar Assad's regime, killing at least five people and wounding scores of others, activists and a rights group said.
Activists said a school employee was killed and several students hurt, four seriously, when a shell exploded near a school bus.
Security forces in several other parts of the country fired on crowds holding overnight demonstrations, causing casualties, activists said.
The new attack using military forces pointed to Assad's determination to crush the two-month-old revolt, despite U.S. and European sanctions, including an EU assets freeze and a visa ban on Assad and nine members of his regime.
The uprising, which began in mid-March, is posing the most serious challenge to his family's 40-year rule. What began as a disparate movement demanding reforms has grown into a resilient uprising seeking Assad's ouster. Human rights groups say more than 1,000 people have been killed in the crackdown.
Sunday's military attacks targeted the towns of Rastan, Talbiseh and Teir Maaleh in the central province of Homs. Authorities had sealed off and isolated the towns by closing roads and cutting phone service, the activists said.
"The towns are under siege," one of the activists said.
The activists spoke on condition of anonymity, fearing government reprisals.
Residents of the towns have held anti-regime protests since the start of the uprising. Those protests have increased recently, with crowds taking to the streets day and night to call for the fall of Assad's regime, an activist said.
The Syrian Observatory for Human Rights said two people were killed in Rastan and four were wounded in Talbiseh. There were no immediate reports of casualties in Teir Maaleh.
An activist said at least three people were killed in Tabliseh. The activist said that nearly 100 wounded people were taken to hospitals in the central city of Homs.
The Local Coordination Committees in Syria, which help organize the protests, said security forces were detaining men in Talbiseh. They said people were blindfolded before being loaded to buses that took them to detention centers.
Also Sunday, human rights activist Mustafa Osso said security forces opened fire at about 8,000 protesters in the northeastern town of Deir el-Zour, wounding several people. He said there were protests overnight in several parts of Syria, including the Damascus suburbs of Zabadani and Douma.
In recent days, many Assad opponents have been holding protests and candlelight vigils at times of the night when the security presence has thinned out.
Osso said armed forces were also conducting operations in the southern village of Hirak, near the city of Daraa, where the uprising began.
Tanks have been used against Syrian cities and towns in the past weeks and major military operations were conducted in areas such as Daraa, the coastal town of Banias and the western town of Talkalakh near the border with Lebanon.
Al-Jazeera TV aired an amateur video from Daraa showing five wounded Syrian soldiers lying on the floor of what appeared to be a hospital. It quoted activists as saying the five soldiers were shot by some of their comrades after they refused to open fire at protesters.
The authenticity of the footage could not be verified, and the network did not say when it was recorded.
Syria has prevented journalists from operating freely in the country and has banned entry to many foreign reporters, including from The Associated Press.
Bassem Mroue can be reached at http://twitter.com/bmroue