Opposition: 88 killed in 'barbaric act' in central Syria Syrian military officers inspect a damaged bus following a deadly explosion Wednesday. NEW: An opposition group says militias "slaughtered entire families in cold blood" Graphic video purports to show the bodies of child victims "Do something," an activist begs the international community More than 300 people are wounded, says another opposition group (CNN) -- Syrian government forces pounded the central province of Homs on Friday, killing 88 people -- some of them children -- an opposition group said. "This barbaric act was preceded by the regime's mortar shelling in the town," the Local Coordination Committees of Syria (LCC) said in a statement, referring to Hawleh, a town in the suburbs of Homs. The campaign ended when the armed militias slaughtered entire families in cold blood. The group described the attack as a massacre. We in the Local Coordination Committees are pained by the international community's apparent blindness to the bloodshed, and believe the United Nations Security Council (UNSC) bears the responsibility for its inability to protect Syrian civilians. We request that the UNSC now take a step forward and more forcefully express its position with regard to the regime's practices," the group said. Another opposition group, the Syrian Observatory for Human Rights, said more than 300 people were wounded in the onslaught and that 13 children were killed. "It's unbelievable that we have seven billion people on this planet, and they all can't do anything about what they are seeing on TV," Abu Emad, an activist, told CNN from Homs. "Do something," he begged the international community. Graphic video posted on YouTube purports to show the lifeless bodies of several small children killed in Hawleh. They are spread on the floor amid blankets, caked in blood. One child is turned to reveal a head wound. Look, these are just children. It is a massacre," a man can be heard shouting. CNN could not independently confirm the authenticity of the video. In other clashes, at least 10 civilian and opposition fighters were injured in a reported assault on the area known as the Mountain of the Kurds near the Turkish border, the Syrian Observatory for Human Rights reported. Four government troops died, the group said. Helicopters fired Friday night on several locations in Idlib province, including Kinda village, Kabaneh, Aako and Abu Risha in Jabal Akrad, according to the LCC. Several people were reportedly wounded, the group said. Government forces also shelled opposition sites in the Homs neighborhoods of Sultanieh and Jobar as people gathered for Friday protests, opposition activists said. In Aleppo, armored vehicles were seen in the streets for the first time since the uprising in Syria began in March 2011, the Syrian Observatory for Human Rights reported. CNN cannot independently confirm reports from within Syria because the government strictly limits access by foreign journalists. In another development Friday, 11 Lebanese Shiite pilgrims abducted in Syria were freed, Lebanese Prime Minister Najib Mikati's office said in a statement. They were in Turkey on Friday and were expected back in Beirut shortly, according to the statement. The incident raised tensions in Lebanon, with protesters in the mainly Shiite areas of southern Beirut taking to the streets Tuesday and Wednesday. Meanwhile, the United Nations said there is no fallback plan to deploying monitors to some of the nation's most embattled cities. However, they have not managed to halt the violence, he said. Ban said the full cadre of observers -- 300 -- authorized by the United Nations Security Council last month would be on site in the coming days. "Gross violations continue unabated," the commission's report said, adding that regime forces commit most of the human rights violations. About 40 civilians were killed across the country Thursday, the LCC said. Opposition groups report a death toll of more than 11,000 people. The report pointed to bombing attacks in Damascus, Aleppo and Daraa between March and May, including suicide car bombings in Damascus on May 10 that left 55 people dead. CNN's Richard Roth, Hamdi Alkhshali, Joe Sterling, Nada Husseini, Amir Ahmed and Kamal Ghattas contributed to this report.