BEIRUT  - An explosion in a car wash in the northern Syrian city of Aleppo killed at least five people on Saturday, activists said, while another blast in the capital destroyed nine cars.
 
Bomb attacks have grown more common in Syria's two largest cities as the uprising against President Bashar Assad grows increasingly militarized. Many in the opposition have taken up arms since protesters first took to the street in March 2011 and now regularly clash with government forces around the country.
 
But Aleppo and Damascus have remained largely in Assad's grip, shaken only by bomb blasts that often appear to target buildings associated with the military and security services.
 
Also Saturday, an explosive planted under an army vehicle in Damascus blew up, damaging nine cars.
  
No one immediately claimed responsibility for the explosions.
 
Earlier this week, attacks on a government security compound and the country's central bank killed nine and injured 100.

The U.N. says more than 9,000 people have been killed since the uprising's start.

World powers remain divided on how to stop Syria's crisis, though all have fallen in behind a plan put forward by former U.N. Secretary General Kofi Annan that seeks a cease-fire in order for all sides to engage in political dialogue.
 
But the truce that was to begin on April 12 has never really taken hold, with regime forces continuing to shell opposition areas and shoot at protesters. Security forces killed one teenager following a protests in the northern city of Aleppo on Friday.

A U.N. team of up to 300 members is to monitor compliance with the truce. U.N. peacekeeping chief Herve Ladsous said about 40 U.N. observers are on the ground in Syria and that the force will grow to 65 by Sunday.