People stand amid wreckage, after three blasts ripped through Aleppo's main Saadallah Al-Jabari Square, and a fourth was reported a few hundred meters away near Bab Al-Jinein, Wednesday. (Inset) Dead men lie on the ground after the blasts. — Reuters BEIRUT — Three suicide bombers Wednesday detonated cars packed with explosives in the main square of the northern city of Aleppo, killing at least 48 people, leveling buildings and trapping survivors under the rubble, Syrian state TV said. A fourth explosion a few hundred meters away also struck near the edge of the Old City, a Unesco World Heritage site that has seen fierce street fighting between rebels and government forces. There was no immediate claim of responsibility, but the government blamed its opponents and said the blasts were caused by suicide bombers. The bloodshed comes amid growing concerns that extremists such as Al-Qaida are making inroads inside Syria. The Syrian opposition denies any links to terrorists, but an extremist group called Jabhat Al-Nusra, or Victory Front, has claimed responsibility for past bombings. Long free of the violence that has engulfed much of the rest of the country, Aleppo in the past two months has become a key battleground between regime forces and rebels trying to oust President Bashar Al-Assad. The opposition launched an initial offensive on the city, Syria's largest and a commercial hub, in July. Large swaths of the ancient city have been shattered. The explosions reduced at least one building to a flattened wreck of twisted concrete and metal, and were followed by a volley of mortar bombs into the square and attempted suicide bombings by three rebels carrying explosives, it said. The facades of many buildings overlooking the square were ripped off and a deep crater was gouged in the road. The Syrian Observatory for Human Rights said 48 people were killed, mostly from the security forces, while official news agency SANA put the death toll at 31. Wednesday's attacks in Aleppo followed last week's bombing of the military staff headquarters in Damascus, another strike by Assad's outgunned opponents against bulwarks of his power. The bloodshed also is increasingly spreading outside Syria's borders. On Wednesday, shells fired from inside Syria landed on a home in neighboring Turkey, killing at least six people, including a 6-year-old boy, said Abdulhakim Ayhan, mayor of the Turkish town of Akcakale. The Syria conflict has killed more than 30,000 people, activists say. Sources in Lebanon said seven members of Lebanon's militant group Hezbollah, a close ally of the Syrian president, were killed inside Syria on Sunday in a rocket attack. Three were killed instantly while four others died later of their wounds, they said.— Agencies