Beirut, Rajab 28, 1433, Jun 18, 2012, SPA - Four people were killed in a bomb blast in eastern Syria Monday, activists said, as the chief of the UN observers urged rival factions to allow the evacuation of trapped and wounded civilians in restive areas across the country. Abu Alaa, a commander in the Free Syrian Army, told DPA of continued shelling in the central province of Homs. "Shelling ... is continuous. The siege is now tighter as some of the passageways which we use to smuggle food and medical supplies, fell under the control of government forces," said Alaa. The Chief of the UN observers' mission, General Robert Mood, reiterated his call for rival factions to allow the evacuation of civilians trapped in the crossfire. "The parties must reconsider their position and allow women, children, the elderly and the injured to leave conflict zones without any preconditions and ensure their safety," Mood said in a statement. Activists have said there are an estimated 1,000 families trapped in Homs alone, and scores of wounded people are in need of urgent medical assistance. --SPA 12:01 LOCAL TIME 09:01 GMT www.spa.gov.sa/1008619