The fighters ambushed four cars late on Thursday and a van on the main road linking Larbaa to Tablat in Medea region and opened fire, they said.
  
They then set fire to the vehicles. One person was injured, the sources added. 
  
The ambush came a day after President Abd al-Aziz Butaflika gave an address to the nation in which he claimed security had been largely reestablished across the country.
  
He said this had been made possible by sacrifices by the security forces under the leadership of the army.
  
"Civil peace has been restored in our society thanks to the benefits of civil harmony immediately transformed into national reconciliation," Butaflika said.
  
About 50 people, including about 15 security force members, have been killed in violence involving armed groups since the beginning of last month, according to a toll compiled using official figures and media reports. 
   
1992 elections cancelled

The Islamic Salvation Front rose up in arms in 1992 when the army annulled a second round of general elections it had won.
  
The low-level civil war reached its murderous heights in the 1990s when bomb attacks and massacres of civilians were frequent.
  
In February, Butaflika put the official death toll from the insurgency at 150,000, and said it had caused economic losses estimated at $30 billion.