ANTAKYA, Turkey — Activists reported new violence in southwest Syria on Saturday, saying shelling by troops and clashes between soldiers and rebel fighters in the city of Dara’a had killed 17 people, including women and children.

The Syrian Observatory for Human Rights, an opposition group based in London with a network of contacts in Syria, said the victims from the violence early on Saturday included 10 women, a 10-year-old girl and two teenage boys. Telephone service, including cellphone networks, had been cut off, the organization said.

Dara’a, near the border with Jordan, is where the uprising against President Bashar al-Assad’s government began in March last year.

In the capital, Damascus, residents on Saturday reported a night of shooting and explosions in the worst violence there since the uprising began, The Associated Press said. For the first time, witnesses said, government tanks opened fire in Damascus, and for nearly 12 hours government forces clashed with armed rebels, who had previously kept a low profile in the capital, The A.P. reported.