At least 13 people have died in a clash between Syrian troops and armed men believed to be military defectors, activists have said.
The clash is the latest sign that the seven-month-old uprising against President Bashar Assad is becoming increasingly militarised.
The troops stormed the north-western town of Binnish with more than 50 vehicles and the sound of explosions and gunfire could be heard.
The London-based Syrian Observatory for Human Rights and another activist group, the Local Co-ordination Committees, said five people were killed.
Rami Abdul-Rahman, who heads the observatory, said six soldiers and two defectors were also killed in the southern village of Harra in the Daraa province.
He said an army force appears to have been ambushed in Harra's main square. Villages and towns in the Daraa province, where the uprising began, have been a hotbed of anti-regime protests from the beginning of the unrest.
Binnish is part of Idlib, a province which borders Turkey, where there have been clashes between the military and army defectors for months.
After months of mostly peaceful protests, the growing involvement of military defectors in confrontations has raised fears that Syria may be sliding toward a civil war.
The uprising against Assad's regime began in mid-March amid a wave of anti-government protests in the Arab world. He has responded with a fierce crackdown, which the UN says has left nearly 3,000 people dead.