The daylight assassination of a top general in a residential neighborhood of the Syrian capital, Damascus, on Saturday underscored the growing militarization of the uprising against the rule of President Bashar al-Assad, and also perhaps its increasing militancy.

According to the state news agency SANA, Brig. Gen. Issa al-Kholi was fatally shot by three gunmen waiting outside his home in the Rukn Eddin neighborhood, which had in the past been one of the few places in the capital to witness large-scale anti-government protests until they were suppressed there last fall.

Kholi is not the first senior military official to be assassinated in recent months, as the protest movement has rapidly evolved in many parts of the country into an armed, if disorganized, insurgency.

But the brazen attack in the center of the normally calm capital, coming a day after twin suicide bombings in the commercial center of Aleppo, heightened the building sense of vulnerability in the two major cities that have remained largely immune to the violence raging elsewhere.

The Local Coordination Committees, an opposition group, said 30 people were killed by security forces on Saturday as the government sustained its assault aimed at crushing the opposition in Homs, several rural suburbs of Damascus and a town in the southern province of Daraa, which are among some of the locations that have in recent months fallen under the sway of the rebel Free Syrian Army.

The spreading violence has heightened concerns that militant groups linked to al-Qaeda may seek to exploit the growing chaos to project their own extremist ambitions onto an uprising that started out as a peaceful protest movement demanding change.

The McClatchy news service on Saturday quoted U.S. officials as saying that al-Qaeda in Iraq was responsible for two suicide bombings that killed 44 people in Damascus on Dec. 23, and also, perhaps, Friday’s bombings in Aleppo, in which 28 people died. The al-Qaeda chief Ayman al-Zawahiri, who is believed to be hiding in Pakistan, ordered operatives of the Iraq-based al-Qaeda affiliate to carry out the attacks, McClatchy said.

Intelligence officials told The Washington Post that while the recent bombings in Syria have the hallmarks of al-Qaeda operations, they have found no conclusive link to al-Qaeda or its Iraqi affiliate.

The officials said, however, that it is plausible that al-Qaeda, marginalized by the recent uprisings across the Arab world, will attempt to insert itself into the effort to topple the Assad regime.

“It wouldn’t be a surprise that al-Qaeda in Iraq — which has operational networks in Syria — would seek to join the opposition and attack the Assad regime,” a U.S. official said.

Miller reported from Washington.