The latest violence came hours before President Liamine Zeroual was to make a speech on nationwide radio and television Friday. Zeroual was expected to say whether he still planned legislative elections by June.
Ten women and two children were among the 15 killed by the unidentified group overnight Thursday, the sources said on condition of anonymity.
There was no claim of responsibility, but suspicion fell on Moslem militants waging a five-year-old insurgency that has left more than 60,000 dead.
The overnight attack brought to 210 the number of people killed since the militants launched an wave of car bombings, massacres and other attacks during the holy month of Ramadan, which began Jan. 10. Five hundred others have been wounded, and most of the victims have been civilians.
The militants seek to undermine efforts by Zeroual's military-backed government to organize legislative elections by mid-year. Zeroual's constitutional reform approved in a disputed referendum in November has outlawed religious-based parties the militants support.
In another massacre Thursday, an armed group slit the throats of 26 people in Benramdane, a village 25 kilometers south of Algiers. Four members of a policeman's family were slain in the same fashion at their home in Baraki, a suburb southeast of the capital, family members said, speaking on condition of anonymity.
On Thursday evening, the mayor of Bachdjarah, a suburb south of Algiers, was shot to death, his family said. They asked that his name not be released.
The Baraki and Bachdjarah suburbs were considered Islamic strongholds two years ago, but repeated operations by security forces were believed to have forced out the militants, and the areas had been considered relatively safe from violence.
In the village of Benramdane, a government-backed "self-defense" group has been active, according to inhabitants.
These groups have become an important part of the government's effort to crush the militants. Organized in 1994, the groups have about 200,000 members, compared to 105,000 troops in Algeria's army. They now have become targets of the militants' attacks.
On Wednesday night, a fifth car bomb in four days killed 10 people and wounded 30 outside a meeting place for militia groups in Boufarik, 40 kilometers south of Algiers, residents said.
Algerian opposition groups criticized the government Thursday for its silence on the wave of violence.
Government-controlled media have only briefly mentioned the attacks, and officials have been completely silent.
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