DAMASCUS, Syria — Facing a growing threat on the doorstep of its capital city, the Syrian government struck out at its opponents in the rebellious eastern suburbs on Sunday, sending soldiers, tanks and armored vehicles to vanquish pockets of rebel fighters in an escalation of the spreading war.

By Monday, the outcome of the military action remained unclear while the Syrian authorities reported violence on a different front, saying a “terrorist group” had blown up a gas pipeline in the central province of Homs near the border with northern Lebanon, according to the official SANA news agency. There have been several such blasts since the revolt against the government of President Bashar al-Assad took root last March. The news agency gave no further details.

Earlier, close to Damascus, columns of black smoke rose from El Ghouta, and heavy clashes were reported in nearby Harasta. A resident who fled Ein Tarma told The Associated Press that electricity and water had been cut to the area during fighting that had not let up since Saturday.

Video shot in Saqba showed soldiers shadowing a tank as it rolled through streets that just days ago were controlled with some swagger by rebel fighters. Activists in Saqba said they knew of at least nine people killed in the fighting on Sunday. That toll could not be independently confirmed.